For Prof tutor Part II...

To evaluate which patients would be higher priority candidates for hippocampal sparing, 3,000 participant treatment plans were evaluated via a cross-sectional differential research method. The method of research used in this study is considered differential and cross-sectional because groups of participants are different ages are compared on a set of variables and because participates of this study were assigned to groups based on preexisting factors.

Patients over the age of 18 and parents of participants under the age of 18 were asked to take part in the research. The aim of research was explained to them and informed consent was obtained by all participants prior to participating in the study. It was explained to participants, or parents of the participants, that data was going to be collected based on the treatment they received and that no additional experimentation with radiation was to be added to their treatment for the benefit of the research study, therefore, there was no additional risk to their treatment plan implemented by this differential research study. The study was subject to external review several credible institutions including the American Society for Therapeutic Radiology and Oncology (ASTRO).

Participants. Participants of this study were subjects who required WBRT and were evaluated in two categories. The two categories were based on treatment intent and will be separated into preexisting palliative and prophylactic categories. With age thought to be the most influential variable, participants in each category were further categorized into two subcategories based on age. Subjects of this study included subcategory A participates who were required to be 25 years of age and younger and subcategory B participants who were required to be 26 years old age and older based on prior research on brain development studies done by Giedd & Rapoport.

The cumulative sample size for the research study was 2,000 participants. 500 subcategory A and 500 subcategory B participants were included in each intent category. Subject exclusions included patients who were on hospice care, those on a concurrent chemotherapy regimen during their radiation therapy treatment and patients who had a treatment plan change after beginning their initially recommended treatment.

Table 1. Visual representation of participants.

Data Collection Method. Data was collected from 20 Radiation Oncologist between 21 different cancer centers over a course of 18 months between January 2014 and June 2015. Two Oncologists at each cancer center participated in the study by collecting research and all had an average of 3 new WBRT patients per month. Each cancer center then treated an average of 6 new WBRT patients per month, 2,000 of which agreed to participate in the study. Data was collected from each physician at the end of each month. The physicians were asked to report on particular variables via a data collection template sheet that was created for this study. Completed data templates were collected on the first of each month for a total of 18 months.

Procedure. To collect primary data, physicians were asked to check a box that indicated treatment intent and another that indicated if the patient was over or under the age of 25. To avoid the common confusion that typically results from the several additional differing variables typically found in differential studies, secondary variables were included in the study. These variables included treatment demand at each facility, which was evaluated by physicians documenting the number days between treatment recommendation and first day of treatment, the urgency of presented symptoms on a scale of 1-10, the risk of cancer spread or progression of disease during the treatment planning process on a scale of 1-10, if the physicians recommend hippocampal sparing and whether or not the patient agreed to the physicians recommendations. These variables were evaluated based on trends and were documented and evaluated helped to explain the rationale behind results of this study.

Results

Results of the study revealed 1,184 participants, or 59% of the population, received conformal treatment with hippocampal sparing. The study revealed that 100% of patients under the age of 25 who are being treated with a prophylactic intent were treated with a hippocampal sparing method. This means that this patient population was declared highest priority and therefore the best candidates for hippocampal sparing with IMRT or IMAT methods above all other candidates who participated in the study. 97%, or 487/500, of patients over the age of 25 who were being treated prophylactically were treated with hippocampal sparing, making the prophylactic category dominant over the palliative category.

Table 2. Visual representation of primary results

With the data collected, the study revealed that candidates were considered a priority in the following descending order:

Table 3. Candidates in descending order

Discussion

The primary variables in this study were treatment intent and age. The study proved that younger patients and those who were being treated with prophylactic intent were more likely candidates for hippocampal sparing with IMRT or IMAT methods. The secondary variables included in this study were used to understand the rationale behind the primary results.

Secondary variable evaluation revealed trends that implied physicians were less likely to recommend a conformal method with hippocampal sparing when patients presented with emergency symptoms that were deemed dangerous or often life threatening such as seizures, strokes or hemorrhages. When a patients risk for their disease progression during the treatment planning process is low they become better candidates for hippocampal sparing. Also, some physicians are more likely to recommend hippocampal sparing than others. Some physicians might be more inclined to treat with a more conventional lateral method because hippocampal sparing has only recently become a popular trend. Patients who are eager to begin treatment might also choose a conformal method rather than an IMRT or IMAT method because it may be less expensive, because it’s a much shorter treatment or because certain patients may be eager to begin treatment would rather not wait the extra time to begin treatment.

Conclusion

Hippocampal sparing is necessary to preserve neurological function when patients are being treated with whole brain irradiation, however, this technique can only be implemented with complex, conformal methods such as IMRT or IMAT that are often time consuming. The research study proved that younger patients who are more likely to survive are of highest priority when it comes to hippocampal sparing methods that preserve the hippocampus to prevent neural stem cell toxicity that could potentially lead to memory loss, decreased IQ or dementia.

References

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Prophylactic under the age of 25

100%

Prophylactic over the age of 25

97%

Palliative under the age of 25

30%

Palliative over the age of 25.

9.40%