Chapter Twenty One
Cancer
Definition
The words cancer and malignancy are commonly used for the medical term neoplasm
Cancer is an abnormal growth of tissue that develops via unregulated cellular
proliferation, shows partial or complete lack of structural organization, lacks functional
coordination with the normal tissue, and usually forms a distinct mass of tissue that may
be either benign or malignant.
Malignant cancers are generally fast growing, have the ability to invade host tissue, are
associated with large areas of necrosis because the tumor outgrows its blood supply, and
can metastasize to other parts of the body.
Pathophysiology
The normal growth and proliferation of cells within the body are under genetic control
The stem cell theory is the model developed to explain the orderly proliferation of cells,
specialization to perform discrete functions, and cell death within an organ.
The stem cell is pluripotent, which means that it is an uncommitted cell with various
developmental options still open. The process by which the pluripotent stem cell is able
to develop special functions and structures an organ system is called differentiation
Some stem cells are triggered to differentiate and become hair cells and others cardiac
myocytes. The pluripotent stem cell has the capacity for self-renewal. After a stem cell
becomes committed to a cell line (e.g. hair cell), it no longer has pluripotent and self-
renewal properties.
See figure 20.1 on stem cell sequence theory
The final common pathway is a cellular genetic mutation that converts a well-behaved
cell into destructive renegade that is unresponsive to the ordinary checks and balances of
the normal community of cells.
In cancer, the cellular DNA of normal stem cells is damaged, leading to disordered cell
growth and specialization
Tumors arise from carcinogenic-causing events occurring within the normal stem cells of
a particular tissue. A cancer-causing insult is believed to produce a defect in the control
of normal stem cell function, resulting in abnormalities in self-renewal, differentiation,
and proliferation; the normal quality and quantity control for cell function and growth is
lost.
Five Broad Categories for Carcinogenic Events
1. Environment: tobacco, obesity and sedentary behavior, infections, radiation, and
pollutants
2. Hereditary: accounts for a small number of all cancers
3. Oncogenes:
a. Normal – acting proto-oncogenes are mutated into oncogenes, which can lead
to tumorigenesis
b. Tumor suppressor genes, which normally function to suppress abnormal cell
growth, can themselves be mutated
4. Hormones; for example, estrogen
5. Impaired immune system function
Four Types
Carcinoma: cancers of epithelial tissues, including cancers of the skin, digestive tract,
genitourinary tract, pulmonary system, and so on; examples are breast, colon, and rectal,
lung, and prostate; carcinomas represent 90% of all cancers
Sarcoma: tumors of the connective tissue, including cancer of the bone, muscles, and
cartilage
Leukemia: cancers of the white blood cells
Lymphoma: cancers of the lymphatic system
Treatment
Surgery: curative versus palliative
Radiation therapy: damages DNA within a cell, applied via implantation (brachytherapy)
from external machine; dose expressed in rads/d, can be used alone or in conjunction
with other therapies; most effective for localized (nonmetastasized) tumors
Chemotherapy: for fast-growing cancers; often used as a curative agent, combination
therapy involves several drugs administered at same time (as a means to minimize any
drug specific cancer resistant effects)
Biotherapy: stimulates the immune response of the body and also involves the production
of antibodies outside the body, which are then administered to the cancer patient in an
attempt to destroy the tumor; includes bone marrow transplantation and the use of
cytokines (e.g., interferon alpha and interleukin-5)
Contraindications to Exercise for Patients with Cancer
Hemoglobin <10.0g/dl
White blood cells <3,000
Platelet count <50*10 9 ml-1
Fever >38 Celsius or 100.4 F
Unsteady gait (ataxia)
Cachexia or loss of >35% of premorbid weight
Limiting dyspnea with exertion
Bone pain
Severe nausea
Extensive skeletal metastases
Exercise Prescription
No evidence supporting a different training response to exercise in the patient with cancer
(vs. healthy adult)
Exercise program should consist of
oAerobic
oResistance
oFlexibility training
Initial modality and intensity modified depending on:
oActive treatment versus survivorship phase
oResponse to treatment (i.e. any adverse reactions)
Consider
oPreexisting comorbidities (e.g. heart disease, osteoarthritis)
oCurrent level of activity
oCurrent functional capacity
oFatigue level
Cardiorespiratory training
oSelect activities that engage large muscle groups such as stationary cycling or
walking
oFrequency: 3 to 5 times per week
oIntensity: (ECG monitoring not warranted)
Sedentary, likely begin at 40 to 50% of heart rate reserve
Currently active, begin at 60% to 80% of heart rate reserve
oDuration: 150 min/wk of moderate exercise or 75 min/wk of vigorous exercise,
varies by individual
Resistance
oIntensity 40% to 70% of 1 RM upper body 50% to 70% of 1RM lower body
oFrequency: two to three times per week
oDuration: one set of 8-12 reps for each muscle group
Special Considerations
Because cancer represents a constellation of diseases and involved organs, learn about the
specific pathology of the cancer involves, common treatments, and treatment side effects
Cancer-related fatigue (CRF) is the most common side effect, >70% in patients
undergoing chemotherapy
Disease – and treatment – related complications are to be expected; modify or withhold
exercise regimen if severe neutropenia, thrombocytopenia, anemia, neuropathy,
lymphedema, or dehydration is present
Powered by TCPDF (www.tcpdf.org)
