Physical activity linked to reduced mortality in breast and colon cancer patients

Physical activity is associated with reduced breast and colon cancer mortality, but there is insufficient evidence on the association for other cancer types, according to a study published May 8 in the Journal of the National Cancer Institute.

Improvements in cancer treatment and screening have allowed cancer survivors to live longer and as a result, cancer survivors frequently look at information about how lifestyle factors like exercise can affect their prognosis. Multiple observational studies and randomized control trials (RCTs) have looked at the effects that physical activity can have on cancer survivors.

To examine the association between physical activity and cancer survival, Rachel Ballard-Barbash, M.D., of the Applied Research Program in the Division of Cancer Control and Population Sciences at the National Cancer Institute and colleagues reviewed 45 articles reporting both observational studies and randomized controlled trials (RCTs) that looked at the relationship between physical activity and mortality and/or cancer biomarkers among cancer survivors. The studies were published between January 1950 and August 2011. The researchers found that the RCTs with biomarker endpoints suggest that exercise may provide benefits to survivors' insulin levels, reduce inflammation, and, possibly, improve immunity. The strongest evidence is for breast cancer survivors: most studies showed a statistically significant reduced risk of breast cancer and all-cause mortality associated with exercise. The next strongest evidence was for colorectal cancer survivors.

The authors point out that because of the diversity of the studies, it would be impossible to extrapolate specific recommendations on type and timing of physical activity. However, they can attest to the overall safety, physical and mental benefits of exercise for cancer survivors. They add that future RCTs should look at different types of exercise, as well as how obesity, weight loss, and cancer treatments may influence the effects of exercise on biomarkers. Also, how exercise may influence comorbidities in cancer survivors should be studied, they write.

Myth: Breast cancer is largely genetic.

Fact: Just 5 to 10% of cases are due to faulty breast cancer genes BRCA1 and BRCA2.
Even in women who have a family history, many cases are due not to specific gene mutations, according to the American Cancer Society, but, rather, to a combination of shared lifestyle factors and genetic susceptibilities. The truth is that scientists still have no idea what causes breast cancer - but new research is shedding light on what makes cancer return.

Myth: Breast cancer always appears as a lump.

Fact: Approximately 10% of those diagnosed with breast cancer have no lumps, pain, or other indications of a problem in their breasts.And among lumps that are detected, 80 to 85% are benign. They're often cysts or noncancerous tumors called fibroadenomas. That said, any lump or breast symptom (especially from the list below) that does not go away should be checked by a doctor.