Obesity & Colorectal Cancer

In early 2012, 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. The discovery of a link between obesity and colorectal cancer could lead to new treatment options in the future. For now, however, the results reinforce the need for people to undergo routine screenings for colorectal cancer starting at age 45. This is especially important for those who are overweight or do not regularly exercise.

Body Fat and Colorectal Cancer Risk

CTNNB1 is a molecule associated with obesity and cancer. The researchers found that for every 11 pounds of body fat (measured by body mass index or BMI) 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.

A patient’s 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. Armed with this information, physicians may recommend have a colonoscopy more frequently than the recommended timeframe of once every 10 years starting at 45.

Why Get a Colonoscopy?

Before getting a screening colonoscopy, it’s important to 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, don’t hurt, and don’t change your bowel habits at all. So there is no way of knowing they are there unless there is an investigation.

A colonoscopy’s advantage over other screening tests is that physicians can take out any polyps detected right then and there. It is, however, a more invasive test that requires anesthesia. But it’s a good option for most patients who are in good general. Other tests for patients who might not tolerate a colonoscopy are barium enemas or x-rays. However, a follow-up colonoscopy will likely be needed to remove any polyps that are discovered.

Screening and Awareness are Making a Difference

The awareness raised in the past decade about the importance of colorectal cancer screening has helped reduce the number of diagnoses. However, the recent data says it’s still the second most common cancer diagnosed in Americans. People still have a 1 in 20 chance of getting colorectal cancer during their lifetimes (NOTE: In 2022 these numbers stand at 1 in 23 for men and 1 in 25 for women). 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 (NOTE: In 2022 these numbers stand at an estimated 151,000 diagnosed cases and 52,500 deaths from colorectal cancer).

Our community’s primary care providers are very good about referring patients when it’s time for a colorectal screening. But we’re learning more about the causes of colorectal cancer every day. That’s why it’s important to understand 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. His office number is 802-254-5510.