Cancer can strike individuals in the prime of their lives, and athletes are no exception.
With advances in screening, diagnosis, and management, people increasingly survive cancer and return to activities that are important to them. According to the National Cancer Institute, there are over 11 million cancer survivors in the United States (44).
Studies indicate that regular exercise can help to prevent certain types of cancer, with the best evidence supporting colon, breast, and endometrial.
Exercise in a cancer patient or survivor has benefits to both health and general well-being.
American College of Sports Medicine (ACSM) position stand on exercise in the cancer survivor was published in 2010 (69).
This was created to highlight new evidence that shows cancer survivors — including those currently undergoing treatment — can experience a multitude of benefits from exercise. They should avoid inactivity and, as closely as possible, adhere to the 2008 federal Physical Activity Guidelines for Americans.
Exercise recommendations should be tailored to the individual cancer survivor to account for exercise tolerance and specific diagnosis. There are certain recommended alterations to the federal physical activity guidelines for specific types of cancer, including breast, prostate, colon, and hematologic (blood or bone marrow).
Sports medicine physicians are ideally positioned to:
Educate athlete about cancer risk
Screen for detectable cancers
Evaluate musculoskeletal pain for potential malignant causes
In conjunction with an athlete and their health care team, develop an exercise program/prescription
Educate on the benefits of exercise in the cancer patient and in cancer prevention
Many sports are played outdoors, and as such, there is sun exposure. Multiple studies have shown an increased risk of skin cancer in outdoor sports, including aquatic and traditionally winter sports (3,34,76).
Radiation exposure may be higher for athletes that travel frequently by airplane and who have multiple x-rays or, especially, computed tomography scans (1,20,24,47).
Skin exposure to trihalomethanes or other carcinogens in swimming pool water has been suggested to be a risk factor for cancer (62).
Drugs or ergogenic aids that may predispose for cancer
Anabolic steroids have traditionally been implicated in hepatoma, and studies show there are sex hormone receptors in liver cancer cells (6,73).
□ Evidence shows individuals with acromegaly have pathologically increased tumor risk.
Erythropoietin (EPO) may lead to angiogenesis and inhibit apoptosis of abnormal cells.
Oral contraceptive pills may increase risk of breast cancer, especially when started before the age of 20 (41,42). Early menarche has also been implicated, and some have theorized that this is an effect of increased estrogen.
Some supplements, including creatine and chromium, are being evaluated for carcinogenicity.
Other risky behaviors
Sexually transmitted diseases that increase risk of cancer (55)
□ Human papillomavirus — cervical cancer, penile cancer
Prolonged strenuous exercise
Most studies show a reduced risk of cancer with exercise; however, there continue to be concerns that prolonged strenuous exercise, such as that encountered by endurance athletes, may lead to an increased risk in certain individuals.
It is theorized that this could be an effect of increased oxidative stress leading to an increased burden of free radicals and significant increases in DNA damage, in conjunction with an observed reversal of the increased activity seen with moderate exercise of macrophages, natural killer cells, and polymorphonuclear neutrophils, which are the first line of defense against cancer.
One study of world-class Norwegian athletes showed a three-fold increased risk of thyroid cancer in female athletes (66).
In vitro and animal studies do suggest that there is an increased incidence of DNA damage as a result of strenuous exercise; however, strenuous exercise has been demonstrated to shrink tumor size (5,7,65).
Human data remain incomplete and inconclusive at this time.
A history of night sweats, fatigue, unintentional weight loss, decreasing performance, treatment-resistant pain, and recurrent infections suggest the need for further investigation.
Social history should be reviewed for risk factors for cancer such as tobacco, environmental exposures, or anabolic steroid use.
A family history of malignancy is important, particularly in cancers that have a strong genetic link.
Table 119.1 Malignant Solid Tumors of the Musculoskeletal System
< 30 years of age; male predominance
60% in the knee; also consider in hip, pelvis, shoulder
“Moth-eaten” or “sunburst” appearance
> 20 years of age
Hip, pelvis, femoral diaphysis, ribs, and proximal humerus
< 30 years of age; male 2:1 predominance
Pelvis, femur, humerus; lucency/lysis; “onion-skin layering”
Giant cell tumors
20-40 years of age; female predominance
Lytic; “soap bubble lesion”
Nonsclerotic, sharply defined borders
90% < 20 years of age
Enlarging, painful, soft tissue mass
Most occur in areas naturally lacking significant skeletal muscle (head, neck, genitourinary tract)
> 50 years of age
Spine or ribs
Mechanical back pain
Lytic, punched out lesions
The physical examination should include a skin examination to exclude melanoma or other skin cancers. Adenopathy, particularly if a mass is enlarging, nontender, and fixed, suggests lymphoma or metastatic disease. Excessive ecchymoses can represent leukemia. Conjunctival pallor from anemia can be present with neoplasm that infiltrates the bone marrow or from occult blood loss in gastrointestinal malignancies. Testicular cancer frequently presents as testicular mass or swelling. The abdomen should be examined for masses and organomegaly.
Cancer can present as musculoskeletal pain and should be considered in the differential diagnosis, especially when certain warning signs are seen, including pain unrelieved by rest, unrelenting pain, night pain, or pain that does not improve despite appropriate treatment. It should also be considered when there are constitutional symptoms that suggest malignancy (10).
Cancers that commonly present as musculoskeletal pain
Metastases, most often from breast, lung, thyroid, kidney, and prostate
□ Bone is third most common site of metastases after lung and liver (10).
□ More common than primary tumors of the bone.
□ More likely to cause significant clinical disease due to pain, pathologic fractures, hypercalcemia, and bone marrow replacement (61).
Solitary primary musculoskeletal tumors including osteosarcoma, chondrosarcoma, Ewing sarcoma, giant cell tumors, and rhabdomyosarcoma (Table 119.1)
Leukemia, lymphoma, and multiple myeloma
There are no specific guidelines for the types of preparticipation evaluation that should be performed on athletes wanting to participate with active cancer; ACSM position stand on exercise guidelines for cancer survivors addressed the preexercise evaluation of survivors.
Consider using multidisciplinary approach to evaluate for individual risk, perceived complications, and clinical status.
Understand that athletes undergoing active cancer treatment can feel profoundly different over short periods of time. They should remain flexible with their exercise program to their changing condition.
Cancer treatments may result in different complications. Chemotherapy, radiation, and hormone therapy can all have side effects that will have a bearing on an individual’s ability to participate in activities. The profile of the specific agents should be understood prior to starting an exercise program.
If surgery has already been performed, evaluate for possible site-specific or regional complications (i.e., wound integrity, lymphedema of the arm or leg with lymph node dissection).
Cardiac complications can be seen with a number of chemotherapy agents, and these may place the athlete at high risk for arrhythmias or cardiomyopathy. There is some evidence to show that stress testing or submaximal stress testing can be used to determine ability to start an exercise program (52).
In the cancer survivor without risk of cardiotoxicity or other specific indications, follow ACSM guidelines for exercise testing before moderate to vigorous aerobic exercise training (69).
Resistance training can be safely undertaken by athletes with active cancer and cancer survivors. Consideration should be given for fracture risk with osteoporosis related to cancer treatment or bony metastases. Also, care must be taken when performing resistance training with abdominal wounds or an ostomy following cancer surgery to decrease risk of herniation by avoiding excessive intra-abdominal pressure (19,69).
Flexibility training may be undertaken safely. Avoid excessive intra-abdominal pressure for athletes with ostomies (69).
There is substantial documentation that physical activity has positive effects on physical and psychological health and overall quality of life (72), and that there is an association between physical activity and breast cancer survival (38,74).
Physical activity is generally well tolerated during and following cancer treatment. A recent meta-analysis showed that the majority of studies find a positive and significant impact of physical activity intervention during treatment for upper and lower body strength and self-esteem. Following treatment, a positive and significant impact of physical activity interventions was seen for aerobic fitness, upper and lower body strength, lower body flexibility, lean body mass, overall quality of life, and cancer-related fatigue (CRF) (72). Although the power of this study may be limited by the fact that approximately 80% of the patients in these studies had breast cancer, there have been promising results noted for prostate and hematologic cancers as well (69).
Despite the documented benefits of exercise, only 25%-30% of cancer survivors are reported to be physically active (defined as meeting the public health exercise guidelines) (30). Young age, higher education, male gender, healthy weight, and absence of comorbidity are positively associated with physical activity among cancer survivors (8,13,40
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