Health Matters Blog

New Study Links Obesity and Colorectal Cancer

By Greg Gadowski

Back in February, just before the start of Colorectal Cancer Awareness Month, the Dana-Farber Cancer Institute in Boston published results of a new study linking obesity and inactivity with an increased risk for a subtype of colorectal cancer known in the medical world as CTNNB1-negative. Such a discovery could lead to new treatment options sometime in the distant future. For now, however, the results reinforce the need for people ages 50 and over to undergo routine screenings for colorectal cancer, especially if they are overweight or do not regularly exercise.

Gregory R. Gadowski, MD, FACS

Gregory R. Gadowski, MD

CTNNB1 is a molecule associated with obesity and cancer. What the researchers found was that for every 11 pounds of body fat (measured by body mass index) a participant’s risk for CTNNB1-negative colorectal cancer increased by about one-third. Meanwhile, the study also found that people who took part in 30 minutes of moderately intense exercise at least four to five times a week reduced their risk by 20-30 percent. The risk of another form of the cancer known as CTNNB1-positive was not impacted by BMI or physical activity, according to the researchers.

Body mass index, also known as BMI, and exercise regimen are just two pieces of information gathered during a screening for colorectal cancer. It’s also important to know whether any close relatives of the patient have had colorectal cancer. After gathering all of this information, the physician might recommend the patient have a colonoscopy more frequently than the recommended timeframe of once every 10 years.

Before getting a screening colonoscopy, it’s important the patient understand why it’s necessary. Colorectal cancer is basically silent at the early stages. It generally starts as a polyp, and the polyps do not cause any symptoms. They don’t bleed. They don’t hurt. They don’t change your bowel habits at all. So there is no way of knowing they are there unless there is an investigation.

The advantage that a colonoscopy has over other screening tests is that physicians can take out any polyps detected right then and there. It is a more invasive test that requires anesthesia. But for most patients that are in good general health we will choose that option. Other tests for patients who might not tolerate a colonoscopy are barium enemas or x-rays. But if a polyp is detected that patient will likely have to have a colonoscopy afterwards to remove it.

The awareness raised in the past 10 to 15 years about the importance of colorectal cancer screening has helped reduce the number of diagnoses. However, the most recent data says that it is still the second most common cancer diagnosed in Americans, just behind skin cancer, and that people still have a 1 in 20 chance of getting colorectal cancer during their lifetimes. An estimated 140,000 new cases of colorectal cancer will be diagnosed this year, according to the American Cancer Society, with approximately 50,000 deaths caused by the disease.

I think the primary care providers in our community are very good about referring patients when it’s time for a colorectal screening. But as we learn more about what causes colorectal cancer, it’s important to remind everyone that there’s more to prevention than just having the colonoscopy. Who you are and how you live your life can also make a difference. Make sure you ask questions and share information about your health and family history during medical visits.

Gregory Gadowski, MD is a board-certified surgeon practicing at Brattleboro General Surgery, which is part of BMH Physician Group. He can be reached at 802-254-5510.

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