Though it's at the other end of the gut, recent studies in the prevention of colon cancer have shown a direct link with weight (BMI) plus moderate exercise (walking). Here's an article that appeared in MedScape. There's some technical parts, but I think you'll get the gist of it. More evidence of the link between cancer and inflammation.
Walking Improves Cancer Outcomes
John L. Marshall, MD
Mar 15, 2013
Hello, everyone. This is John Marshall for Medscape. Let me ask you a question: How much exercise did you get this week? I am in training with a team for a big, long race. We are exercising to get ready for that, so last week I ran almost 14 miles total. I was quite proud of myself. (I am hurting so much this week that I can't run at all, but that's another story.)
What do you think about running, exercise, and physical activity and your risk of developing cancer? A lot of data is emerging on this subject. Just in the last few months, 2 very interesting studies have been published on the relationship between exercise, physical activity, body mass index, and colorectal cancer. I thought it would be useful to pause and think about this a bit.
The data from the larger of these studies come from Harvard's Nurses' Health Study and the Health Professionals Follow-Up Study. It includes roughly 150,000 people. Every year these participants receive a long survey asking, for example, "How much broccoli do you eat? How much exercise do you get?" In essence, the answers provide a snapshot of participants' nutrition and exercise for the whole year. Of course, we assume that these people are pretty good reporters and give us pretty good data, although if you asked me today how much exercise I get I would say a lot, whereas if you had asked me a few months ago, I might have answered differently. So, there is an innate problem with this kind of survey data but they overcome that with size. Around 150,000 people were involved in the larger study, and 2300 people were involved in the other.
The Beta-catenin Connection
Let me focus on the one from the Harvard group first. Of the 150,000 people surveyed, 861 patients developed colon cancer. This group of 861 patients with colon cancer has been studied several times, but in this analysis, investigators looked at the Wnt/beta-catenin pathway that was measured within their tumors and then cross-referenced that with physical activity and body mass index.
They found that body mass index and physical activity correlated with the kind of cancer you got. If you did not have this Wnt/beta-catenin pathway upregulated and you had a high body mass index, you were at higher risk for the tumor being beta-catenin-negative.
[This suggests the possibility of] a metabolic reason or a gene pathway linking overweight and inactivity with the kind of colon cancer a person develops. This is great science and great for hypothesis generation. Would I start testing everyone's tumor for this? No. It is more of a mechanistic kind of study.
Walking Improves Outcomes
The second study is "ready for prime time" and applicable in your clinic if you are not doing it already. In this study, published in the Journal of Clinical Oncology in January, investigators identified 2300 people [with invasive, nonmetastatic colorectal cancer] and measured how much exercise they got before and after their diagnosis. This is fascinating data, showing that those people who were more physically active both before and after their diagnosis of colon cancer had much better outcomes.
These patients needed only a minimum 8.75 MET (metabolic equivalent) hours of recreational exercise per week, or the equivalent of 150 minutes a week of physical activity -- basically, walking. So, I often prescribe a dog for patients because they will have to walk their dog. Insurance won't cover that, by the way. We have tried.
If you engage in that much physical activity before and after [a colon cancer diagnosis] the risk reduction [in all-cause mortality] is 0.58. That is better than any chemotherapy we have ever given to anyone. Physical activity after diagnosis, and certainly pre- and post-, is better, but even if you just pick it up afterwards, you will have a significant improvement in outcome. If you are a couch potato and do not exercise, your risk goes the other way, to risk escalation, with a 1.36 hazard ratio [for all-cause mortality].
Exercise should be an important part of every discussion that we have with patients with colorectal cancer. I think the same type of data is available in breast cancer. Whenever I have finished with adjutant therapy in a patient, I give them this talk. I prescribe the dog and make sure they exercise. I know my colleagues around the country do this as well. You need to harp on patients: "Now is the time for intensive physical activity. You always said that you wanted to get in shape. Well, now is a good time to do it, and with good reason, because the magnitude of benefit of the physical activity may be, in fact, greater than the magnitude of chemotherapy."
The next time you find yourself in one of those difficult conversations with patients who have stage 2 colon cancer and want chemotherapy or something additional, perhaps recommend exercise instead. Better benefit, maybe, than chemotherapy.
This is John Marshall for Medscape. Go and get yourselves some Nikes instead of chemotherapy.
Morikawa T, Kuchibal A, Lochhead P, et al. Prospective analysis of body mass index, physical activity, and colorectal cancer risk associated with â-Catenin (CTNNB1) status. Cancer Res. 2013;73:1600-1610. Abstract
Campbell PT, Patel AV, Newton CC, et al. Associations of recreational physical activity and leisure time spent sitting with colorectal cancer survival. J Clin Oncol. 2013;31:876-885. Abstract
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