Friday, August 15, 2008

Times to me: 'Get off the couch!'

I wasn't going to comment on the New York Times cancer and exercise story (I don't want to be a NYT clipping service), but I kept thinking about the article hours after reading it, specifically this part:
Other studies indicate that moderate exercise has additional benefits like strengthened immune function and lower rates of recurrence. Studies at Dana-Farber found that nonmetastatic colon cancer patients who routinely exercised had a 50 percent lower mortality rate during the study period than their inactive peers, regardless of how active they were before the diagnoses.
I wondered how they figured that out, so I read a little more about the 2006 study. It made sense to me that having a more serious presentation of colon cancer would make you more likely to be sedentary after treatment and also more likely to die from a recurrence or other cause. I wanted to see how they adjusted for that. The study's authors say they can't completely eliminate that possibility, but they picked patients at the same stage of the disease who had similar surgery and chemotherapy, adjusted the data for other risk factors of death, and eliminated from the study population people who died within six months of having their physical activity assessed. That said, the study doesn't have much to say about causation or the mechanism by which exercise might lower recurrence risk. 

Nonetheless, an editorial published along with the study used these results and others relating to breast cancer to tell patients that it's "time to get moving." If you're tempted, exercise seems to provide measurable benefits at about 9 MET hours  a week (don't ask; it's the equivalent of four or five 30-minute brisk walks) after breast cancer and 18 weekly MET hours (four or five 30-minute jogs) after colon cancer. Shockingly, there's no epithelioid sarcoma data. I don't know if working out that much is possible for me, but I'm at least going to take a walk this afternoon...

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