Physical Activity Linked to Better Survival in Men With Colorectal Cancer
By Laurie Barclay, MD
Medscape Medical News
December 14, 2009 — In men with a history of nonmetastatic colorectal cancer, more physical activity was associated with a lower risk for colorectal cancer–specific and overall mortality, according to the results of a large cohort study reported in the December 14/28 issue of the Archives of Internal Medicine.
"Although physically active individuals have a lower risk of developing colorectal cancer, few studies have examined whether exercise benefits colorectal cancer survivors," write Jeffrey A. Meyerhardt, MD, MPH, from Dana-Farber Cancer Institute, Harvard Medical School and Massachusetts General Hospital in Boston, and colleagues.
Using data from the Health Professionals Follow-up Study, the investigators examined colorectal cancer–specific and overall mortality rates, based on predefined physical activity categories after diagnosis, in 668 men who had a history of stage I to stage III colorectal cancer and no apparent metastases at diagnosis. Men who died within 6 months of their postdiagnosis physical activity evaluation were excluded to reduce bias related to occult recurrences.
More than half (50.4%) of the study cohort exercised 18 metabolic equivalent task (MET) hours per week or more. Increased physical activity was significantly associated with lower colorectal cancer–specific mortality rate (P = .002 for trend) and lower overall mortality rate (P < .001 for trend). Compared with men who participated in 3 or less MET hours per week of physical activity, those who participated in more than 27 MET hours per week of physical activity had an adjusted hazard ratio for colorectal cancer–specific mortality of 0.47 (95% confidence interval, 0.24 - 0.92). Age, disease stage, body mass index (BMI), diagnosis year, tumor location, and physical activity before diagnosis did not appear to affect the apparent benefit of physical activity.
"In a large cohort of men with a history of nonmetastatic colorectal cancer, more physical activity was associated with a lower risk of colorectal cancer–specific and overall mortality," the study authors write.
Limitations of this study include lack of data on cancer recurrences beyond cause of mortality, lack of treatment data, homogeneous nature of the cohort, and possible confounding by comorbidities and access to healthcare. In addition, data were limited to leisure-time exercise and did not include occupational physical activity.
"These results provide further support that physical activity after colorectal cancer diagnosis may lower the risk of death from that disease," the study authors write. "A randomized study among high-risk stage II and stage III colon cancer survivors that will compare the use of general education materials with a program that includes supervised physical activity sessions and behavioral support delivered over 3 years will soon open; the primary end point is disease-free survival. The findings from the present study further support that effort."
In an accompanying editorial, Janet E. Fulton, PhD, from the Centers for Disease Control and Prevention in Atlanta, Georgia, and colleagues note the increasing evidence that a physically active lifestyle benefits health.
"As we look to the future, a better understanding of the science of physical activity is essential," the editorialists write. "Learning how best to promote the findings of that science for public consumption and adoption is equally vital....Even small physical activity contributions to a diverse physical activity portfolio can produce multiple health dividends."
The National Institutes of Health supported this study. The study authors and editorialists have disclosed no relevant financial relationships. The opinions of the editorialists do not necessarily represent the official position of the Centers for Disease Control and Prevention or the National Heart, Lung, and Blood Institute.
