Annotated bibliography about 3 peers reviewed references

Simon et al. Arthritis Research & Therapy (2015) 17:212 DOI 10.1186/s13075-015-0728-9

RESEARCH ARTICLE Open Access

Incidence of malignancy in adult patients with rheumatoid arthritis: a meta-analysis

Teresa A. Simon1*, Adam Thompson1, Kunal K. Gandhi1, Marc C. Hochberg2 and Samy Suissa3

Abstract

Introduction: Patients with rheumatoid arthritis (RA) are at an increased risk of malignancies compared with the general population. This has raised concerns regarding these patients, particularly with the widespread use of immunomodulating therapies, including biologic disease-modifying antirheumatic drugs (DMARDs). We performed a systematic literature review and analysis to quantify the incidence of malignancies in patients with RA and the general population to update previously published data.

Methods: A literature search was conducted that was consistent with and similar to that in a meta-analysis published in 2008. MEDLINE, BIOSIS Previews, Embase, Derwent Drug File and SciSearch databases were searched using specified search terms. Predefined inclusion criteria identified the relevant observational studies published between 2008 and 2014 that provided estimates of relative risk of malignancy in patients with RA compared with the general population. Risk data on overall malignancy and site-specific malignancies (lymphoma, melanoma and lung, colorectal, breast, cervical and prostate cancer) were extracted. The standardized incidence ratios (SIRs; a measure of risk) relative to the general population were evaluated and compared with published rates.

Results: A total of nine publications met the inclusion criteria. Seven of these reported SIRs for overall malignancy; eight for lymphoma, melanoma, and lung, colorectal and breast cancer; seven for prostate cancer; and four for cervical cancer. Compared with those in the general population, the SIR estimates for patients with RA suggest a modest increased risk in overall malignancy, as previously observed. Patients with RA continued to show an increased risk of lymphoma and lung cancer compared with the general population. Overall, SIR estimates for colorectal and breast cancers continued to show a decrease in risk, whereas cervical cancer, prostate cancer and melanoma appeared to show no consistent trend in risk among patients with RA compared with the general population.

Conclusions: The additional data evaluated here are consistent with previously reported data. Patients with RA are at an increased risk of lung and lymphoma malignancies compared with the general population. Quantifying differences in malignancy rates between non-biologic and biologic DMARD-treated patients with RA may further highlight which malignancies may be related to treatment rather than to the underlying disease.

Introduction Rheumatoid arthritis (RA) is a polygenic, multifactorial and chronic immune-mediated disease characterized by chronic joint inflammation, a predilection for develop- ment of joint damage and deformity, and extraarticular involvement [1]. The management of RA includes the use of biologic and non-biologic disease-modifying anti- rheumatic drugs (DMARDs) [2, 3], which act by directly modifying immunologic pathways involved in the patho- genesis of RA. The risk of malignancy among patients

* Correspondence: [email protected] 1Bristol-Myers Squibb, Princeton, NJ, USA Full list of author information is available at the end of the article

© 2015 Simon et al. Open Access This articl International License (http://creativecommo reproduction in any medium, provided you link to the Creative Commons license, and Dedication waiver (http://creativecommons article, unless otherwise stated.

with RA has been of ongoing interest and research be- cause of the autoimmune pathogenesis that underlies RA, the common etiology between rheumatic disease and malignancy, and the use of immunomodulatory therapy, such as DMARDs, that may alter normal immu- nosurveillance and elevate the risk of malignancy [4, 5]. Understanding this potential therapeutic risk has be- come more relevant with the increasing use of biologic DMARDs as a routine therapeutic approach to RA man- agement [3]. With more biologic treatment options avail- able and initiation of biologic treatments occurring earlier, it is important to understand the baseline risk of malig- nancies in patients with RA. Furthermore, continuous

e is distributed under the terms of the Creative Commons Attribution 4.0 ns.org/licenses/by/4.0/), which permits unrestricted use, distribution, and give appropriate credit to the original author(s) and the source, provide a indicate if changes were made. The Creative Commons Public Domain .org/publicdomain/zero/1.0/) applies to the data made available in this

Simon et al. Arthritis Research & Therapy (2015) 17:212 Page 2 of 10

updates on the incidence of malignancies published in the literature are crucial to allow better understanding of the background rates for malignancy in clinical trials and ob- servational research evaluating real-world practice. Smitten et al. [6] performed a meta-analysis on the

risk of overall malignancy and several site-specific can- cers, including overall lymphoma, Hodgkin disease, non- Hodgkin lymphoma, lung cancer, colorectal cancer and breast cancer, using data published between 1990 and 2007. Their meta-analysis suggested a small overall in- crease in risk of malignancy, which was elevated for lymphoma, Hodgkin disease, non-Hodgkin lymphoma and lung cancer, but they found a decreased risk of colo- rectal and breast cancer in patients with RA compared with the general population [6]. The malignancies in- cluded were prespecified and based on the most fre- quently reported malignancies in an RA population. In this article, we review the data on the incidence of

malignancy reported since the Smitten et al. [6] meta- analysis and additionally evaluate the risk of other im- portant site-specific malignancies, namely, melanoma, cervical cancer and prostate cancer, which have been a topic of discussion in recent publications [7–9].

Methods Literature search We conducted a search of the MEDLINE, BIOSIS Previews, Embase, Derwent Drug File and SciSearch databases for literature published between 1 January 2008 and 30 November 2014, using the following specified search terms: cancer or tumor, tumour, malign* and rheu- matoid arthritis or RA, and epidemiolog* or inciden*, population, observation, retrospective or occurren*.

Exclusion algorithm Predefined inclusion criteria were used to identify rele- vant observational studies that provided estimates of relative risk of malignancy in patients with RA compared with the general population. The same criteria as de- tailed by Smitten et al. [6] were applied. Studies were eli- gible for inclusion if they fulfilled the following criteria: (1) observational study design (including prospective, retrospective, epidemiologic, database, survey, registry, cohort and case–control), (2) reported malignancy out- comes in patients with RA and a general population, (3) enrolled more than 100 patients, (4) included only patients older than 18 years of age, (5) covered any geographic region and (6) were reported in English as a full-length publication. Citations meeting the inclusion criteria were obtained and screened for the outcomes of interest, which included the observed incidence rates of total malignancy and lymphoma, lung, colorectal, breast, melanoma, prostate and cervical cancers in patients with RA compared with the expected incidence rates in the

general population. Lymphoma was reported as Hodgkin or non-Hodgkin where available. The selection of studies for inclusion was made without regard to evaluation of specific RA management strategies. We attempted to avoid overlap by excluding studies for which updated publications were available. We also excluded studies that compared specific RA biologic treatments with other RA treatments, unless overall RA and general population rates were reported.

Data presentation Citations meeting the inclusion criteria were screened for outcomes of interest. Risk data on overall malignancy and site-specific malignancies (overall lymphoma, Hodgkin disease, non-Hodgkin lymphoma, melanoma, and lung, colorectal, breast, cervical and prostate cancers) were extracted independently by two people and compared for accuracy. Study-specific estimates of relative risk were measured mostly by overall and age- and sex-adjusted standardized incidence ratios (SIRs) relative to non-RA patients or the general population. In one study using a case–control approach, researchers reported an odds ratio, which is an accurate estimator of the relative risk [10]. Thus, all measures of relative risk and their res- pective 95 % confidence intervals (CIs) were then com- pared with previously published rates. Pooled relative risks and 95 % CIs were then computed using the DerSimonian and Laird technique [11], in which a random-effects model takes into consideration both within-study and between-studies variation by incorporating the hetero- geneity of the effects in the overall analysis. Some studies in which authors reported data separately for colon and rectal cancer, or for men and women, were considered separate studies when we pooled relative risks.

Results A total of 136 articles were identified using the defined search criteria (Fig. 1). Following identification, a total of 33 potential publications were further analyzed; of these, 9 studies met all the inclusion criteria (Fig. 1) [10, 12–19]. These studies included population- and community-based RA cohorts, examined data from 458 to 84,475 patients and had mean follow-up periods ranging from 4 to 25 years. The relative risk of overall malignancy was reported in seven studies [12–15, 17–19]; lymphoma (overall lymphoma, Hodgkin disease or non-Hodgkin lymphoma), lung, colorectal and breast cancers and mel- anoma in eight [10, 12–17, 19]; prostate cancer in seven [10, 12–17]; and cervical cancer in four [12, 14, 16, 17]. Overall risk by malignancy type was reported in eight studies [10, 12–17, 19], both overall risk and risk by sex were reported in three [15, 17, 18] and risk stratified by sex only was reported in one [16].

136 publicatio ns identified

129 unique publications

121 publications

–7 duplicate publications

61 publications

33 publications

21 publications

15 publications

11 publications

10 publications met inclusion criteria (1 publication was previously cited in

Smitten et al. [6] as in press and therefore was not included)

–8 non-English publications

–60 not full manuscript publication s (i.e. meeting abstracts)

–28 not observational-type studies (i.e. reviews, meta-analyses, case reports)

–12 did not compare data to general population

–6 did not report malignancy outcome s

–4 did not report incidence data

–1 reported malignancy not evaluated in this publication

Fig. 1 Literature search data

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Overall malignancies In general, SIRs for overall malignancy across the studies were similar. Six of seven studies reported a significant in- crease in overall risk of malignancy (Fig. 2) [12–15, 17–32]. The total pooled SIR (95 % CI) for studies analyzed by Smitten et al. (1.05 [1.01–1.09]) [6] and those included here was significant: 1.09 (1.06–1.13). With the addition of the newer studies, there was no change in the overall sum- mary statistic showing that patients with RA have a 10 % increase in overall malignancy risk compared with the general population.

Lymphoma In eight studies, authors reported outcomes as either overall lymphoma, Hodgkin disease or non-Hodgkin lymphoma [10, 12–17, 19]. Two studies reported only lymphoma, whereas the remaining six studies reported overall lymphoma, Hodgkin disease and non-Hodgkin lymphoma rates, with all of the new studies reporting a sig- nificant increase in risk of lymphoma in patients with RA compared with the general population (Figs. 3, 4 and 5). This ranged from almost a doubling (SIR 1.75) (Fig. 3) [10, 15, 17, 21, 23, 24, 29, 30, 33] to a 12-fold increase

(SIR 12.82) (Fig. 4) [12, 14–16, 19, 22, 24, 25, 27–29, 34, 35] in the risk of developing lymphoma. The pooled SIR for Hodgkin disease (Fig. 4) was higher than for non-Hodgkin lymphoma (Fig. 5) [12–16, 19, 20, 22, 24, 25, 27–29, 34–36]. The total pooled SIR (95 % CI) for the studies reviewed here and by Smitten et al. [6] was 2.46 (2.05–2.96) for ma- lignant lymphoma, 3.21 (2.42–4.27) for Hodgkin disease and 2.26 (1.82–2.81) for non-Hodgkin lymphoma. The overall risk with the addition of the new studies is con- sistent with previously reported SIRs (2.08 [1.80–2.39], 3.29 [2.56–4.22] and 1.95 [1.70–2.24], respectively) [6]; however, a slight increase in risk for non-Hodgkin disease was noted.

Lung cancer In eight studies, authors reported that patients with RA had an increased risk of lung cancer compared with the general population [10, 12–17, 19]. The SIRs (95 % CI) for lung cancer ranged from 1.36 (1.34–1.38) to 2.9 (1.6–4.8) (Fig. 6) [10, 12–17, 19–22, 24–28, 32, 36–38]. The total pooled SIR (95 % CI) for the studies reviewed here and by Smitten et al. [6] was 1.64 (1.51–1.79) for lung cancer. The risk of lung cancer in patients with RA compared

Source n/N SIR (95% CI) Matteson 1991 (DMARDs) [32] 20/530 1.52 (0.90, 2.6)†

Gridley 1993 [24] 840/11,683 0.95 (0.9, 1.0) Moritomo 1995 [26] 26/655 1.38 (0.90, 2.02)

Kauppi 1996 [31] 540/9469 1.16 (1.07, 1.26) Mellemkjaer 1996 [25] 1832/20,699 1.08 (1.03, 1.13)§

Cibere1997 [22] 136/862 0.8 (0.67, 0.95) Thomas 2000 [27] 2029/26,623 1.01 (1.0, 1.1) Ekstrom 2003 [29] 8896/76,527 1.07 (1.05, 1.09) Askling 2005 [21] 3379/53,067 1.05 (1.01, 1.08)

Askling 2005 (early RA) [21] 138/3703 1.1 (0.9, 1.3)‡

Askling 2005 (anti-TNF) [21] 67/4160 0.9 (0.7, 1.2)‡

Geborek 2005 [30] 69/800 1.4 (1.1, 1.8)‡

Geborek 2005 (anti-TNF) [30] 16/757 1.1 (0.6, 1.8) Abasolo 2007 [20] 25/789 1.2 (0.8, 1.8)†

Franklin 2007 [23] 92/1237 1.1 (0.9, 1.3)†

Wolfe 2007 [28] 543/13,869 1.0 (1.0, 1.1)†

Buchbinder 2008 [19] 64/458 1.5 (1.2, 1.9) Hemminki 2008 [14] 4366/42,262 1.23 (1.19, 1.27)

Chen 2011 [12] 935/23,644 1.12 (1.11, 1.13) Yamada 2011 [17] 173/7566 1.18 (1.02, 1.37)

Female* 1.13 (0.94, 1.36) Male* 1.29 (0.99, 1.67)

Kim 2012 [18] 30/1501 0.86 (0.58, 1.23) Female* 0.99 (0.65, 1.42) Male* 0.31 (0.04, 1.11)

Dreyer 2013 [13] 128/3812 1.25 (1.05, 1.48) Mercer 2013 [15] 182/3771 1.28 (1.10, 1.48)

Female* 1.38 (1.15, 1.64) Male* 1.11 (0.85, 1.44)

Total pooled SIR 23 1.09 (1.06, 1.13)

0.1 10.01.0

New studies

Fig. 2 Relative risk of overall malignancy in patients with rheumatoid arthritis (RA) compared with the general population. CI, confidence interval; DMARD, disease-modifying antirheumatic drug; n, number of malignancies; N, population size; RR, relative risk; SIR, standardized incidence ratio; TNF, tumor necrosis factor. *SIRs by sex are not included in the total pooled SIR. †Excluding non-melanoma skin cancer. ‡All solid tumors. §Excluding lymphatic and hematopoietic

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with the general population in the contemporary study is consistent with what was previously observed (1.63 [1.43–1.87]) [6].

Colorectal cancer In seven studies [12, 14–17, 19], authors reported that patients with RA had a decreased risk of colon or colorectal cancer, with SIRs (95 % CI) ranging from 0.49 (0.26–0.83) to 0.96 (0.56–1.54) (Fig. 7) [10, 12–17, 19–22, 24–28, 31, 36]. However, in some studies, authors reported SIRs >1, with the highest being 1.53 (0.69–3.42)

Source n/N Gridley 1993 [24] 48/11,683

Ekstrom 2003 [29] 535/76,527

Askling 2005 [21] 319/53,067

Askling (early RA) [21] 11/3703

Askling 2005 (anti-TNF) [21] 9/4160

Geborek 2005 [30] 2/800

Geborek 2005 (anti-TNF) [30] 5/757

Franklin 2007 [23] 9/1237

Wolfe 2007 [33] 95/19,591

Hellgren 2010† [10] 19/6745

Yamada 2011 [17] 20/7566

Female*

Male*

Mercer 2013 [15] 21/3771

Female*

Male*

Total pooled SIR 12

0

New studies

Fig. 3 Relative risk of malignant lymphoma in patients with rheumatoid ar interval; n, number of malignancies; N, population size; OR, odds ratio; SIR, are not included in the total pooled SIR. †Reported as odds ratio

for rectal cancer [10, 13]. For colorectal cancer, the total pooled SIR (95 % CI) for the studies reviewed by Smitten et al. (0.77 [0.65–0.90]) [6] plus those included here was 0.78 (0.71–0.86).

Breast cancer For breast cancer, there was generally no increase in risk; estimated risk varied from 0.63 to 1.21 in the new studies [10, 12–17, 19] (Fig. 8) [10, 12–17, 19–22, 24–28, 36]. The total pooled SIR (95 % CI) for the studies reviewed by Smitten et al. (0.84 [0.79–0.90]) [6]

SIR (95% CI)

1.75

1.98 (1.5, 2.6)

2.00 (1.83, 2.17)

1.9 (1.7, 2.1)

2.0 (1.1, 3.5)

2.9 (1.3, 5.5)

1.3 (0.2, 4.5)

11.5 (3.7, 26.9)

2.94 (1.34, 5.57)

1.8 (1.5, 2.2)

(1.04, 2.96)

6.07 (3.71, 9.37)

6.00 (3.28, 10.07)

6.22 (2.28, 13.54)

3.81 (2.36, 5.82)

3.73 (1.98, 6.37)

3.95 (1.71, 7.79) 2.46 (2.05, 2.96)

30.01.0

thritis (RA) compared with the general population. CI, confidence standardized incidence ratio; TNF, tumor necrosis factor. *SIRs by sex

Parikh-Patel 2009 [16]

Source n/N SIR (95% CI)

Gridley 1993 [24] 12/11,683 2.34 (1.2, 4.1) Mellemkjaer 1996 [25] 14/20,699 3.4 (1.8, 5.6)

Cibere 1997 [22] 0/862 0.0 (0.00, 8.53) Kauppi 1997 [34] 4/9469 2.2 (0.6, 5.7)

Thomas 2000 [27] 17/26,623 3.85 (2.2, 6.2) Mariette 2002 (MTX) [35] 7/30,000 7.4 (3.0, 15.3)

Ekstrom 2003 [29] 77/76,527 3.06 (2.42, 3.83) Wolfe 2007 [28] 4/13,869 3.0 (1.3, 6.8)

Buchbinder 2008 [19] 1/458 8.9 (0.2, 49.8) Hemminki 2008 [14] 35/42,262 4.05 (2.82, 5.63)

25/84,475 Female* 1.62 (0.91, 2.68) Male* 2.76 (1.32, 5.08)

Chen 2011 [12] 1/23,644 1.76 (1.45, 2.17) Mercer 2013 [15] 5/3771 12.82 (4.16, 29.92)

Total pooled SIR 14 3.21 (2.42, 4.27)

0 50.01.0

New studies

Fig. 4 Relative risk of Hodgkin disease in patients with rheumatoid arthritis (RA) compared with the general population. CI, confidence interval; n, number of malignancies; N, population size; MTX, methotrexate; SIR, standardized incidence ratio. *SIRs by sex for Parikh-Patel et al. [16] are included in the total pooled SIR, as overall SIR was not available in their study

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plus those included here was found to be 0.86 (0.73–1.01) for breast cancer.

Melanoma and cervical and prostate cancers As previously noted, we included three additional malig- nancies (melanoma and cervical and prostate cancer) in our assessment that were not included in the Smitten et al. meta-analysis [6]. Figs. 9, 10 and 11 highlight the ar- ticles analyzed by Smitten et al. [6] and the newer studies included in our assessment. For melanoma, we reviewed 17 studies (9 from Smitten et al. [20–22, 24–28, 36] and 8 new [10, 12–17, 19]). Of these, the overall range of SIRs was 0.3–8.83, and five studies [12, 14, 19, 28, 36] showed a significant increase in the risk of melanoma in the RA population, ranging from 1.29 to 3.0 (Fig. 9) [10, 12–17, 19–22, 24–28, 36]. The total pooled SIR was 1.23 (1.01– 1.49). For cervical cancer, SIRs were reported in a total of 13

studies (nine from Smitten et al. [20–22, 24–28, 36] and

Source n/N Gridley 1993 [24] 36/11,683

Mellemkjaer 1996 [25] 85/20,699 Cibere 1997 [22] 3/862 Kauppi 1997 [34] 34/9469

Mariette 2002 [35] 18/30,000 Thomas 2000 [27] 101/26,623 Ekstrom 2003 [29] 458/76,527

Setoguchi 2006 (DMARDs) [36] 58/7830 Abasolo 2007 [20] 3/789

Wolfe 2007 [28] 42/13,869

Buchbinder 2008 [19] 8/458 Hemminki 2008 [14] 280/42,262

Parikh-Patel 2009 [16] 325/84,475 Female* Male*

Chen 2011 [12] 59/23,644 Dreyer 2013 [13] 5/3812 Mercer 2013 [15] 16/3771

Female* Male*

Total pooled SIR 17

0.1

New studies

Fig. 5 Relative risk of non-Hodgkin lymphoma in patients with rheumatoid interval; DMARD, disease-modifying antirheumatic drug; n, number of malig sex included in total pooled SIR only if overall SIR was not available

four new [12, 14, 16, 17]). Overall, the range of SIRs was 0.43–2.15, and all confidence intervals were overlapping (Fig. 10) [12, 14, 16, 17, 20–22, 24–28, 36]. In three studies, authors reported a significant decrease in risk compared with the RA population [12, 16, 36]. The total pooled SIR for cervical cancer was 0.87 (0.72–1.05). For prostate cancer, SIRs were reported in a total of 15 studies (8 from Smitten et al. [20–22, 24, 25, 27, 28, 36] and 7 new [10, 12–17]). Overall, the range of SIRs was 0.35–3.20, and the total pooled SIR was 1.15 (0.98–1.34) (Fig. 11) [10, 12–17, 20–22, 24, 25, 27, 28, 36].

Discussion Although individual studies can show considerable vari- ation, the results of this updated meta-analysis of the incidence of malignancy in adult patients with RA are generally consistent with previously reported data for all specific malignancies [6]. The updated data reported here show that patients with RA have a modest increased risk

SIR (95% CI) 1.88 (1.3, 2.6) 2.4 (1.9, 2.9) 0.55 (0.11, 1.60) 2.2 (1.5, 3.1) 1.07 (0.6, 1.7) 2.13 (1.7, 2.6) 1.89 (1.72, 2.07) 2.2 (1.71, 2.87) 5.4 (1.1, 15.7) 1.7 (1.3, 2.2)

5.1 (2.2, 10.0) 2.34 (2.07, 2.63)

1.37 (1.19, 1.57) 2.07 (1.71, 2.48) 3.54 (3.45, 3.63) 2.27 (0.94, 5.45) 3.12 (1.79, 5.07) 3.39 (1.69, 6.07) 2.66 (0.86, 6.21) 2.26 (1.82, 2.81)

20.01.0

arthritis (RA) compared with the general population. CI, confidence nancies; N, population size; SIR, standardized incidence ratio. *SIRs by

0.1 50.01.0

Source n/N SIR (95% CI) Matteson 1991 (DMARDs) [32] 6/530 3.37 (1.58, 7.34)

McKendry 1993 (MTX) [37] 4/144 12.4 (3.38, 31.84) Gridley 1993 [24] 68/11,683 1.31 (1.0, 1.7)

Mo ritomo 1995 [26] 0/655 0 (0, 1.82) Kauppi 1996 [38] 73/8920 1.8 (1.4, 2.2)

Mellemkjaer 1996 [25] 308/20,699 1.5 (1.3, 1.7) Cibere 1997 [22] 16/862 1.08 (0.61, 1.75)

Thomas 2000 [27] 472/26,623 1.39 (1.3, 1.5) Askling 2005 [21] 330/53,067 1.48 (1.33, 1.65)

Askling 2005 (early RA) [21] 23/3703 2.4 (1.5, 3.6) Askling 2005 (anti-TNF) [21] 10/4160 1.8 (0.9, 3.3)

Setoguchi 2006 [36] 169/7830 1.8 (1.52, 2.05) Abasolo 2007 [20] 7/789 3.5 (1.4, 7.1)

Wolfe 2007 [28] 112/13,869 1.2 (1.0, 1.4)

Buchbinder 2008 [19] 14/458 2.9 (1.6, 4.8) Hemminki 2008 [14] 448/42,262 1.73 (1.57, 1.89)

Parikh-Patel 2009 [16] 1178/84,475 Female* 1.28 (1.19, 1.38) Male* 1.65 (1.49, 1.81)

Hellgren 2010† [10] 34/6745 2.24 (1.49, 3.36) Chen 2011 [12] 123/23,644 1.36 (1.34, 1.38)

Ya mada 2011 [17] 34/7566 2.29 (1.57, 3.21) Female* 1.66 (0.89, 2.85) Male* 3.02 (1.85, 4.67)

Dreyer 2013 [13] 20/3812 1.67 (1.08, 2.59) Mercer 2013 [15] 46/3771 2.39 (1.75, 3.19)

Female* 2.66 (1.79, 3.80) Male* 2.01 (1.15, 2.36)

Total pooled SIR 23 1.64 (1.51, 1.79)

New studies

Fig. 6 Relative risk of lung cancer in patients with rheumatoid arthritis (RA) compared with the general population. CI, confidence interval; DMARD, disease-modifying antirheumatic drug; MTX, methotrexate; n, number of malignancies; N, population size; SIR, standardized incidence ratio; TNF, tumor necrosis factor. *SIRs by sex are included in total pooled SIR only if overall SIR was not available. †Reported as odds ratio

Simon et al. Arthritis Research & Therapy (2015) 17:212 Page 6 of 10

of overall malignancy as well as an increased risk of lung cancer and lymphoma when compared with the general population. Lymphoma was associated with the greatest relative risk, especially Hodgkin disease, with a 12-fold in- crease reported in one study [15] and an increase in women versus men in another [16]. Lung cancer generally showed a twofold increase in risk [10, 12–17, 19]. As

Fig. 7 Relative risk of colorectal cancer in patients with rheumatoid arthritis (R DMARD, disease-modifying antirheumatic drug; n, number of malignancies; N factor. *SIRs by sex are included in total pooled SIR only if overall SIR was not

previously noted, a decreased risk overall of colorectal cancer in patients with RA compared with the general population was found. For melanoma, the pooled SIR was significantly greater than unity, although few of the indi- vidual point estimates were statistically significant. Breast and cervical cancers in general showed a decrease in risk overall that failed to reach statistical significance.

A) compared with the general population. CI, confidence interval; , population size; SIR, standardized incidence ratio; TNF, tumor necrosis available. †Reported as odds ratio

Source n/N SIR (95% CI) Gridley 1993 [24] 106/11,683 0.79 (0.6, 1.0)

Moritomo 1995 [26] 3/655 1.68 (0.34, 4.91) Mellemkjaer 1996 [25] 186/20,699 0.8 (0.7, 0.9)

Cibere 1997 [22] 18/862 0.9 (0.46, 1.24) Thomas 2000 [27] 249/26,623 0.95 (0.83, 1.07) Askling 2005 [21] 471/53,067 0.83 (0.76, 0.91)

Askling 2005 (early RA) [21] 13/3703 0.6 (0.3, 1.0) Askling 2005 (anti-TNF) [21] 8/4160 0.4 (0.2, 0.9)

Abasolo 2007 [20]2007 [20] 2/789 0.9 (0.1, 3.2) Setoguchi 2006 (DMARDs) [36] 112/7830 0.9 (0.73, 1.06)

Wolfe 2007 [28] 102/13,869 0.8 (0.6, 0.9)

Buchbinder 2008 [19] 4/458 0.7 (0.2, 1.7) Hemminki 2008 [14] 642/42,262 0.97 (0.90, 1.05)

Parikh-Patel 2009 [16] 842/84,475 0.63 (0.59, 0.67) Hellgren 2010* [10] 42/6745 0.89 (0.64, 1.23)

Chen 2011 [12] 123/23,644 1.21 (1.19, 1.23) Yamada 2011 [17] 20/7566 1.05 (0.64, 1.62)

Dreyer 2013 [13] 14/3812 0.89 (0.53, 1.51) Mercer 2013 [15] 30/3771 1.07 (0.72, 1.52)

Total pooled SIR 19 0.86 (0.73, 1.01)

0.1 10.01.0

New studies

Fig. 8 Relative risk of breast cancer in patients with rheumatoid arthritis (RA) compared with the general population. CI, confidence interval; DMARD, disease-modifying antirheumatic drug; n, number of malignancies; N, population size; SIR, standardized incidence ratio; TNF, tumor necrosis factor. *Reported as odds ratio

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Various explanations for the differences observed in the risk of certain malignancies in patients with RA have been proposed. It is thought that ongoing immunologic stimulation over time may increase the risk of malignant transformation of immune system cells and decrease the number of T-suppressor lymphocytes, thus increasing rates of lymphoma malignancy in patients with RA [4]. Chronic lung inflammation due to the disease in patients with RA may explain the increased risk of lung cancer. Smoking increases the risk of both RA and lung cancer; however, the SIRs reported here were not adjusted for smoking, so it is not possible to rule out the increase in

Askling 2005 (anti-TNF) [21]

Source n/N Gridley 1993 [24] 12/11,683

Female* Male*

Moritomo 1995 [26] 1/655 Female*

Mellemkjaer 1996 [25] 37/20,699 Female* Male*

Cibere 1997 [22] 45/862 Thomas 2000 [27] 28/26,623

Female* Male*

Askling 2005 [21] 120/53,067 Askling 2005 (early RA) [21] 4/3703

1/4160 Setoguchi 2006 (DMARDs) [36] 29/7830

Abasolo 2007 [20] 1/789 Male*

Wolfe 2007 [28] 32/13,869

Buchbinder 2008 [19] 7/458 Hemminki 2008 [14] 143/42,262

Parikh-Patel 2009 [16] 184/84,475 Female* Male*

Hellgren 2010† [10] 11/6745 Chen 2011 [12] 3/23,644

Yamada 2011 [17] 4/7566 Female* Male*

Dreyer 2013 [13] 3/3812 Mercer 2013 [15] 9/3771

Female* Total pooled SIR 21

0

New studies

Fig. 9 Relative risk of melanoma in patients with rheumatoid arthritis (RA) co disease-modifying antirheumatic drug; n, number of malignancies; N, populat *SIRs by sex are included in total pooled SIR only if overall SIR was not availab

SIR being due to an indirect association. Thus, the risk of both lymphoma and lung cancer has been hypothe- sized to be dependent on the level of disease activity ex- perienced by the patient [4, 6]. Patients with RA continued to show no increase in

overall risk of colorectal and breast cancers, in contrast to their increased risk for lung cancer and lymphoma. In patients with RA, any observed decreased risk in colo- rectal malignancy may be due to the increased use of non-steroidal anti-inflammatory drugs, which are known to decrease this risk [4, 6]. Overall, the risk of malig- nancy among patients with RA may be due in part to

SIR (95% CI) 0.93 (0.5, 1.16) 1.23 (0.6, 2.2) 0.25 (0, 1.4) 8.83 (0.12, 49.10) 13.3 (0.17, 74.0) 1.1 (0.8, 1.5) 1.1 1.3 0.83 (0.63, 1.16)

1.21 (0.79, 1.77) 0.34 (0.04, 1.22) 1.19 (0.99, 1.42) 0.9 (0.2, 2.2) 0.3 (0.0, 1.8) 2.3 (1.55, 3.22) 3.8 (0.1, 21.0) 17.1 (0.4, 95.2) 1.7 (1.3, 2.3)

3.0 (1.2, 6.2) 1.29 (1.09, 1.52)

0.63 (0.51, 0.76) 0.80 (0.63, 1.00) 1.04 (0.54, 1.99) 1.47 (1.31, 1.65) 2.34 (0.64, 6.00) 1.66 (0.20, 6.01) 3.96 (0.48, 14.30) 1.00 (0.32, 3.11) 2.05 (0.94, 3.90) 2.05 (0.75, 4.46) 1.23 (1.01, 1.49)

100.01.0

mpared with the general population. CI, confidence interval; DMARD, ion size; SIR, standardized incidence ratio; TNF, tumor necrosis factor. le. †Reported as odds ratio

Source n/N SIR (95% CI) Gridley 1993 [24] 17/11,683 0.9 (0.5, 1.4)

Moritomo 1995 [26] 3/655 2.15 (0.43, 6.27) Mellemkjaer 1996 [25] 40/20,699 1.1 (0.8, 1.5)

Cibere 1997 [22] 1/862 0.49 (0.06, 2.76) Thomas 2000 [27] 26/26,623 0.89 (0.58, 1.31) Askling 2005 [21] 33/53,067 1.03 (0.71, 1.45)

Askling 2005 (early RA) [21] 1/3703 0.8 (0.02, 4.3) Askling 2005 (anti-TNF) [21] 1/4160 1.0 (0.0, 5.8)

Setoguchi 2006 (DMARDs) [36] 16/7830 0.5 (0.31, 0.82) Abasolo 2007 [20] 1/789 1.0 (0.1, 22.7)

Wolfe 2007 [28] 4/13,869 0.8 (0.4, 1.9)

Hemminki 2008 [14] 58/42,262 1.26 (0.95, 1.62) Parikh-Patel 2009 [16] 47/84,475 0.43 (0.31, 0.57)

Chen 2011 [12] 45/23,644 0.86 (0.84, 0.89) Yamada 2011 [17] 4/7566 1.36 (0.37, 3.49) Total pooled SIR 15 0.87 (0.72, 1.05)

0 30.0 1.0

New studies

Fig. 10 Relative risk of cervical cancer in patients with rheumatoid arthritis (RA) compared with the general population. CI, confidence interval; DMARD, disease-modifying antirheumatic drug; n, number of malignancies; N, population size; SIR, standardized incidence ratio; TNF, tumor necrosis factor

Simon et al. Arthritis Research & Therapy (2015) 17:212 Page 8 of 10

the autoimmune pathogenesis of RA and common etiology between RA and malignancy, including genetic factors, smoking-related tissue necrosis and viral infec- tion [9]. The three other site-specific malignancies ex- amined here but not studied previously by Smitten et al. [6]—prostate cancer, cervical cancer and melanoma—are all common cancers, with cervical cancer being attribut- able to viral infection. In the present analysis, there did not appear to be a consistent trend of increased or de- creased risk of prostate cancer, cervical cancer or melan- oma among patients with RA compared with the general population. One review published in 2008 that did not meet our criteria showed melanoma results that were con- sistent with our present assessment. Some populations showed an increase in risk, whereas others did not [8]. This review, like that of Smitten et al. [6], is based on

observational, real-world clinical data; however, these in- dividual studies may have potential limitations. Although most of the individual estimates were derived from simi- lar database studies, their study designs (including popu- lations, data sources, follow-up times, data analysis and

Fig. 11 Relative risk of prostate cancer in patients with rheumatoid arthritis n, number of malignancies; N, population size; SIR, standardized incidence

procedures of reporting, particularly when linked to a cancer registry) were a source of heterogeneity among the studies and may be associated with bias of varying magnitude. In addition, other potential sources of hetero- geneity included geography and/or region, stage and se- verity of RA, and treatment. Such heterogeneity should be considered in any meta-analysis; the DerSimonian and Laird technique used in this study [11] assumes hetero- geneity across studies and incorporates it into the esti- mation of the pooled SIRs and their confidence limits. Therefore, although the variation observed among the in- dividual SIRs reported should be treated with caution when interpreting these data, it should be recognized that this variation was accounted for in the analyses resulting in the pooled SIRs. For example, with regard to treatment, Dreyer et al. [13]

evaluated the effect of tumor necrosis factor (TNF) inhibi- tor treatment on risk rate by examining the treated and non-treated populations separately (only non-treated data included in this analysis), whereas Mercer et al. [15] evaluated biologic-naive patients. Buchbinder et al. [19]

(RA) compared with the general population. CI, confidence interval; ratio. *Reported as odds ratio

Simon et al. Arthritis Research & Therapy (2015) 17:212 Page 9 of 10

examined malignancy risk only in patients with RA receiv- ing methotrexate. However, the rest of the patients in these studies are likely to have received treatments for RA, therefore making it difficult to differentiate the effects of treatment and disease. Nonetheless, to further under- stand which malignancies may be related to treatment ver- sus the underlying disease, it is important, where possible, to quantify differences in malignancy rates between pa- tients with RA treated with non-biologic DMARDs and those treated with biologic DMARDs. Whether biologic agents, predominantly TNF inhibitors, increase the risk of malignancy has been debated [9]. Data have shown that use of TNF inhibitors was not associated with a major further increase in risk in the already elevated lymphoma occurrence in patients with RA [39–44]. However, they do appear to increase the risk of skin cancer, including melanoma [39–43]. Furthermore, the data presented by Simon et al. suggest that the observed incidence of total malignancy and those for breast, colorectal and lung can- cers and lymphoma in patients treated with abatacept was largely consistent with that expected of patients with RA treated with non-biologic DMARDs [45].

Conclusions The additional data presented here are consistent with previously reported data [6] for all specified malignancies. For overall malignancy, the new studies analyzed here show a similar increase in risk compared with that pre- viously reported. In addition, patients with RA continue to be at an increased risk of lung cancer and lymphoma when compared with the general population. Further studies examining specific aspects such as treatments, smoking or other lifestyle factors are needed to investigate the under- lying mechanisms for the increased or decreased risk of specific cancers observed in patients with RA compared with the general population. Also, it is important to quan- tify any differences in malignancy risks between patients with RA who are treated with non-biologic DMARDs and those treated with biologic DMARDs, as understanding which malignancies may be related to the treatment as opposed to being related to underlying disease will allow patients to be advised and monitored accordingly.

Abbreviations CI: confidence interval; DMARD: disease-modifying anti-rheumatic drug; MTX: methotrexate; NR: not reported; OR: odds ratio; RA: rheumatoid arthritis; RR: relative risk; SIR: standardized incidence ratio; TNF: tumor necrosis factor.

Competing interests TAS and KKG are employees and stockholders of Bristol-Myers Squibb. AT is an intern at Bristol-Myers Squibb and a medical student at Rowan University School of Osteopathic Medicine, Stratford, NJ, USA. MCH receives grant/ research support from the National Institutes of Health and is a consultant for Bristol-Myers Squibb, Eli Lilly, EMD Serono, Genentech/Roche, Novartis Pharma AG, Pfizer and UCB. SS is a consultant for Bristol-Myers Squibb and Genentech/Roche. The authors declare that they have no non-financial competing interests.

Authors’ contributions TAS participated in the design and coordination of data collection, contributed to analysis and interpretation of data and helped to draft the manuscript. AT conducted the literature search and helped to draft the manuscript. KKG contributed to the study design and data collection and interpretation and helped to draft the manuscript. MCH contributed to the study design and interpretation of the data and helped to draft the manuscript. SS contributed to the study design, performed the meta-analysis, contributed to data interpretation and helped to draft the manuscript. All authors read and approved the final manuscript.

Acknowledgments Bristol-Myers Squibb funded the study and reviewed and approved the manuscript before its submission. The authors had ultimate control over the decision to publish and the final version of the manuscript submitted for publication. The authors thank Julia Chuang of Bristol-Myers Squibb for providing research assistance. Professional medical writing and editorial assistance was provided by Fiona Boswell at Caudex and was funded by Bristol-Myers Squibb.

Author details 1Bristol-Myers Squibb, Princeton, NJ, USA. 2Departments of Medicine and Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA. 3Division of Clinical Epidemiology, McGill University, Montreal, QC, Canada.

Received: 13 May 2015 Accepted: 24 July 2015

References 1. Aletaha D, Neogi T, Silman AJ, Funovits J, Felson DT, Bingham 3rd CO, et al.

2010 rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum. 2010;62:2569–81.

2. Smolen JS, Landewé R, Breedveld FC, Dougados M, Emery P, Gaujoux-Viala C, et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs. Ann Rheum Dis. 2010;69:964–75.

3. Singh JA, Furst DE, Bharat A, Curtis JR, Kavanaugh AF, Kremer JM, et al. 2012 update of the 2008 American College of Rheumatology recommendations for the use of disease-modifying antirheumatic drugs and biologic agents in the treatment of rheumatoid arthritis. Arthritis Care Res (Hoboken). 2012;64:625–39.

4. Love T, Solomon DH. The relationship between cancer and rheumatoid arthritis: still a large research agenda. Arthritis Res Ther. 2008;10:109.

5. Cush JJ, Dao KH. Malignancy risks with biologic therapies. Rheum Dis Clin North Am. 2012;38:761–70.

6. Smitten AL, Simon TA, Hochberg MC, Suissa S. A meta-analysis of the incidence of malignancy in adult patients with rheumatoid arthritis. Arthritis Res Ther. 2008;10:R45.

7. Kim SC, Glynn RJ, Giovannucci E, Hernández-Díaz S, Liu J, Feldman S, et al. Risk of high-grade cervical dysplasia and cervical cancer in women with systemic inflammatory diseases: a population-based cohort study. Ann Rheum Dis. 2015;74:1360–7.

8. Chakravarty EF, Farmer ER. Risk of skin cancer in the drug treatment of rheumatoid arthritis. Expert Opin Drug Saf. 2008;7:539–46.

9. Szekanecz Z, Szekanecz É, Bakó G, Shoenfeld Y. Malignancies in autoimmune rheumatic disease – a mini-review. Gerontology. 2011;57:3–10.

10. Hellgren K, Smedby KE, Feltelius N, Baecklund E, Askling J. Do rheumatoid arthritis and lymphoma share risk factors? A comparison of lymphoma and cancer risks before and after diagnosis of rheumatoid arthritis. Arthritis Rheum. 2010;62:1252–8.

11. DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials. 1986;7:177–88.

12. Chen YJ, Chang YT, Wang CB, Wu CY. The risk of cancer in patients with rheumatoid arthritis: a nationwide cohort study in Taiwan. Arthritis Rheum. 2011;63:352–8.

13. Dreyer L, Mellemkjær L, Andersen AR, Bennett P, Poulsen UE, Juulsgaard Elligsen T, et al. Incidences of overall and site specific cancers in TNFα inhibitor treated patients with rheumatoid arthritis and other arthritides – a follow-up study from the DANBIO Registry. Ann Rheum Dis. 2013;72:79–82.

Simon et al. Arthritis Research & Therapy (2015) 17:212 Page 10 of 10

14. Hemminki K, Li X, Sundquist K, Sundquist J. Cancer risk in hospitalized rheumatoid arthritis patients. Rheumatology. 2008;47:698–701.

15. Mercer L, Davies R, Galloway JB, Low A, Lunt M, Dixon WG, et al. Risk of cancer in patients receiving non-biologic disease-modifying therapy for rheumatoid arthritis compared with the UK general population. Rheumatology (Oxford). 2013;52:91–8.

16. Parikh-Patel A, White RH, Allen M, Cress R. Risk of cancer among rheumatoid arthritis patients in California. Cancer Causes Control. 2009;20:1001–10.

17. Yamada T, Nakajima A, Inoue E, Tanaka E, Taniguchi A, Momohara S, et al. Incidence of malignancy in Japanese patients with rheumatoid arthritis. Rheumatol Int. 2011;31:1487–92.

18. Kim YJ, Shim JS, Choi CB, Bae SC. Mortality and incidence of malignancy in Korean patients with rheumatoid arthritis. J Rheumatol. 2012;39:226–32.

19. Buchbinder R, Barber M, Heuzenroeder L, Wluka AE, Giles G, Hall S, et al. Incidence of melanoma and other malignancies among rheumatoid arthritis patients treated with methotrexate. Arthritis Rheum. 2008;59:794–9.

20. Abásolo L, Júdez E, Descalzo MÁ, González-Álvaro I, Jover JA, Carmona L, et al. Cancer in rheumatoid arthritis: occurrence, mortality and associated factors in a South European population. Semin Arthritis Rheum. 2008;37:388–97.

21. Askling J, Fored CM, Brandt L, Baecklund E, Bertilsson L, Feltelius N, et al. Risks of solid cancers in patients with rheumatoid arthritis and after treatment with tumour necrosis factor antagonists. Ann Rheum Dis. 2005;64:1421–6.

22. Cibere J, Sibley J, Haga M. Rheumatoid arthritis and the risk of malignancy. Arthritis Rheum. 1997;40:1580–6.

23. Franklin J, Lunt M, Bunn D, Symmons D, Silman A. Influence of inflammatory polyarthritis on cancer incidence and survival: results from a community-based prospective study. Arthritis Rheum. 2007;56:790–8.

24. Gridley G, McLaughlin JK, Ekbom A, Klareskog L, Adami HO, Hacker DG, et al. Incidence of cancer among patients with rheumatoid arthritis. J Natl Cancer Inst. 1993;85:307–11.

25. Mellemkjaer L, Linet MS, Gridley G, Frisch M, Møller H, Olsen JH. Rheumatoid arthritis and cancer risk. Eur J Cancer. 1996;32A:1753–7.

26. Moritomo H, Ueda T, Hiyama T, Hosono N, Mori S, Komatsubara Y. The risk of cancer in rheumatoid patients in Japan. Scand J Rheumatol. 1995;24:157–9.

27. Thomas E, Brewster DH, Black RJ, Macfarlane GJ. Risk of malignancy among patients with rheumatic conditions. Int J Cancer. 2000;88:497–502.

28. Wolfe F, Michaud K. Biologic treatment of rheumatoid arthritis and the risk of malignancy: analyses from a large US observational study. Arthritis Rheum. 2007;56:2886–95.

29. Ekström K, Hjalgrim H, Brandt L, Baecklund E, Klareskog L, Ekbom A, et al. Risk of malignant lymphomas in patients with rheumatoid arthritis and in their first-degree relatives. Arthritis Rheum. 2003;48:963–70.

30. Geborek P, Bladström A, Turesson C, Gulfe A, Petersson IF, Saxne T, et al. Tumour necrosis factor blockers do not increase overall tumour risk in patients with rheumatoid arthritis, but may be associated with an increased risk of lymphomas. Ann Rheum Dis. 2005;64:699–703.

31. Kauppi M, Pukkala E, Isomaki H. Low incidence of colorectal cancer in patients with rheumatoid arthritis. Clin Exp Rheumatol. 1996;14:551–3.

32. Matteson EL, Hickey AR, Maguire L, Tilson HH, Urowitz MB. Occurrence of neoplasia in patients with rheumatoid arthritis enrolled in a DMARD Registry. Rheumatoid Arthritis Azathioprine Registry Steering Committee. J Rheumatol. 1991;18:809–14.

33. Wolfe F, Michaud K. The effect of methotrexate and anti-tumor necrosis factor therapy on the risk of lymphoma in rheumatoid arthritis in 19,562 patients during 89,710 person-years of observation. Arthritis Rheum. 2007;56:1433–9.

34. Kauppi M, Pukkala E, Isomäki H. Elevated incidence of hematologic malignancies in patients with Sjögren’s syndrome compared with patients with rheumatoid arthritis (Finland). Cancer Causes Control. 1997;8:201–4.

35. Mariette X, Cazals-Hatem D, Warszawki J, Liote F, Balandraud N, Sibilia J, et al. Lymphomas in rheumatoid arthritis patients treated with methotrexate: a 3-year prospective study in France. Blood. 2002;99:3909–15.

36. Setoguchi S, Solomon DH, Weinblatt ME, Katz JN, Avorn J, Glynn RJ, et al. Tumor necrosis factor α antagonist use and cancer in patients with rheumatoid arthritis. Arthritis Rheum. 2006;54:2757–64.

37. McKendry RJ, Dale P. Adverse effects of low dose methotrexate therapy in rheumatoid arthritis. J Rheumatol. 1993;20:1850–6.

38. Kauppi M, Pukkala E, Isomäki H. Excess risk of lung cancer in patients with rheumatoid arthritis. J Rheumatol. 1996;23:1484–5.

39. Mariette X, Matucci-Cerinic M, Pavelka K, Taylor P, van Vollenhoven R, Heatley R, et al. Malignancies associated with tumour necrosis factor inhibitors in registries and prospective observational studies: a systematic review and meta-analysis. Ann Rheum Dis. 2011;70:1895–904.

40. Park HJ, Ranganathan P. TNF-α antagonism and cancer risk in rheumatoid arthritis: is continued vigilance warranted? Discov Med. 2012;13:229–34.

41. Le Blay P, Mouterde G, Barnetche T, Morel J, Combe B. Risk of malignancy including non-melanoma skin cancers with anti-tumor necrosis factor therapy in patients with rheumatoid arthritis: a meta-analysis of registries and systematic review. Clin Exp Rheumatol. 2012;30:756–64.

42. Askling J, Fahrbach K, Nordstrom B, Ross S, Schmid CH, Symmons D. Cancer risk with tumor necrosis factor α (TNF) inhibitors: meta-analysis of randomized controlled trials of adalimumab, etanercept, and infliximab using patient level data. Pharmacoepidemiol Drug Saf. 2011;20:119–30.

43. Damjanov N, Nurmohamed MT, Szekanecz Z. Biologics, cardiovascular effects and cancer. BMC Med. 2014;12:48. doi:10.1186/1741-7015-12-48.

44. Askling J, Baecklund E, Granath F, Geborek P, Fored M, Backlin C, et al. Anti-tumour necrosis factor therapy in rheumatoid arthritis and risk of malignant lymphomas: relative risks and time trends in the Swedish Biologics Register. Ann Rheum Dis. 2009;68:648–53.

45. Simon TA, Smitten AL, Franklin J, Askling J, Lacaille D, Wolfe F, et al. Malignancies in the rheumatoid arthritis abatacept clinical development programme: an epidemiological assessment. Ann Rheum Dis. 2009;68:1819–26.

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