Dr. Michael Fulks reviews recent studies suggesting that regular exercise after cancer treatment may significantly reduce recurrence and improve long-term survival.
This truly remarkable result (at least to me) can be found in a recent NEJM article by K.S. Courneya, et al. The authors took patients (mostly in Canada and Australia) with resected stage 3 (or high-risk stage 2) colon cancer who had finished adjuvant chemotherapy (out about 1 year from diagnosis) and randomized them to receive regular active exercise coaching for 3 years vs. education on exercise and nutrition with very long-term follow-up.
Adherence to a program of increased exercise (probably walking or jogging) was high in the active coaching group and exercise tolerance was higher than in the education group but body weights were similar. The 5-year disease-free survival was 80% for those assigned to the exercise group vs. only 74% in the education group with a hazard ratio of 0.72. Over-all 8-year survival was 90% in the exercise group and 83% in the education group. Colon cancer recurred at a 2.5% annual rate for exercise vs. a 3.1% annual rate for education suggesting the survival advantage is likely based mostly on reduced cancer recurrence rather than other causes of mortality. The disease-free survival curves showed a consistent increasing advantage for the exercise group out to 10 years.
After years of observational studies where exercise was linked to cancer survival but with no certainty which was the cause and which the effect and after hearing a host of unsupported claims, this is the first high quality, fully randomized trial of exercise after cancer that I have seen. I reviewed it with skepticism, but the results look valid and robust. Generalization, based on one study, is hazardous, but it appears possible that regular exercise may reduce the risk of cancer recurrence after initial treatment and, one could hope, the overall risk of cancer.
My work with Clinical Reference Laboratory typically involves evaluating testing to better predict future adverse events for the benefit of both individual life insurers and insurance applicants who are then able to use the results to reduce risk. This study serves as a reminder not to forget the known (cardiovascular and mental health) and potential (cancer prevention) benefits of simply exercising regularly. We can only supplement rather than replace that benefit with any testing effort.
About the Author
Michael Fulks, MD, Consulting Medical Director, is board-certified in internal and insurance medicine. After leaving practice, he served as a medical director, creating or editing several underwriting manuals and preferred programs. More recently, Mike has consulted for CRL participating in its mortality research on laboratory test results, BP and build, and in the development of risk-scoring tools for laboratory and non-laboratory data.