Intuition rejects any notion that colon cancer is related to exercise.
The only way to exercise a colon is a five-course meal or a double serving of frijoles. Colon cancer seems obviously caused by carcinogens that come in direct contact with the bowel wall.
Well, that is part of the story.
The connection between exercise and cancer of any kind raises two questions. Is the data right or was my hipshot reaction, my intuition, telling me something?
When our intuition warns us that something doesn’t make sense, there is reason to slow down and take a closer look. If the data supports the claim, it asks us to figure out how it fits in with the bigger picture of health, disease and why we get old.
A traditional Pennsylvania Dutch saying would add: “Why do we get too soon old and too late smart?”
Evidence clearly supports the concept that exercise helps reduce the incidence of many cancers, and it may improve survival in patients who suffer from the disease. Breast cancer incidence is thought to be impacted even more than colon malignancies by exercise.
The issue of overdiagnosing breast cancer may make those claims hard to assess, but the information on colon cancer is strong enough to accept the theory that exercise can change the incidence and prognosis of neoplastic disease.
Mice that eat standard diets form fewer polyps if they exercise on their wheels. The effect doesn’t seem to overcome the impact of a high calorie, American style diet.
The Journal of the National Cancer Institute (JNCI) published a review article on June 6, 2012. It concludes that there “is consistent evidence from 27 observational studies that physical activity is associated with reduced all-cause, breast cancer-specific, and colon cancer-specific mortality.”
The article also concludes there is currently insufficient evidence to show a similar effect for other malignancies.
Explanations of technical terms may seem boring, but bear with me.
• “Cancer specific” indicates that there is an effect of exercise on the cancer, and that patients aren’t living longer because their physical fitness makes them more heart-healthy.
• Better “all-cause” survival tells us that the gain from exercise isn’t offset by a negative effect. It would be possible, for example that exercise caused fractured hips or some other problem.
• Finally, realize that “observational” studies look at groups of people who could be mismatched and the data is less solid than a randomized study.
I’m taking the position that exercise can slow the progression of a malignant process. Without claiming that most cancers can be avoided or that any can be cured, let’s accept the theory that vigorous programs — involving several hours a week and significantly raising your heart rate — has a positive net effect. Let’s go a step further and analyze how it’s possible.
The goal is to understand how lifestyle, diet and other factors affect longevity.
If we, as scientists, as humans, put the pieces together, we might get closer to Ponce de Leon’s dream, a fountain of youth.
A team from the Sloan Kettering Hospital expressed concern that sitting for four or more hours a day may offset the benefits of exercise. They suggest setting a timer and getting up every hour.
I felt that I should add that advice before having you delve into a chemistry book or checking out my claims with an Internet search.
The JNCI article mentioned earlier also tried to find a link connecting physical activity with the failure of our bodies to manage the unrestricted division of cells and their progression to invasiveness and possible death.
At this point, a lot of work is being done on the level of insulin in our bloodstreams, insulin-related chemistry, immunity and inflammation, as well as effects on energy transfer in cells.
If you read my articles about heart attacks, dietary sugar and carnitine, you’ll be ahead of my thinking.
Next month, after one of my articles reviewing the latest scientific literature, I want to introduce the metabolic syndrome. Can reducing sugar intake and exercising religiously combat the cycle that results in cell malfunction? Can we keep body and brain functioning better? What’s possible today and where is research headed tomorrow?
A warning: I’m a physician, but not your physician, nor a world expert on everything. Use my opinions as a way to stimulate interest in learning more about illness and becoming a patient who can have more productive discussions with your personal caregiver.
Dr. Larry Mulkerin is a retired clinical professor and oncologist who lives in Walla Walla. A former U.S. Army Green Berets medical officer with experience in the Middle East, he also is the author of “The Ayatollah’s Suitcase,” a novel available at amazon.com and other online book retailers. He can be reached at firstname.lastname@example.org.