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Massachusetts Medical Society's Physician Focus

May 2016

Colorectal Cancer


  • The American Cancer Society estimates that more than 134,000 cases of colorectal cancer are diagnosed annually.

  • Screening for the disease saves lives, but 23 million American adults – about one in three – do not get screened as recommended.

  • Colonoscopy is the test most likely to find something harmful; it is not just a screening technique, but actually prevents cancer.

Colorectal cancer is the second leading cause of cancer-related death for both men and women in the United States, claiming more than 50,000 lives each year. The important part of the story is that it’s preventable.

“The average American vastly underestimates their risk of colon cancer,” says Francis MacMillan Jr., M.D. “The lifetime risk of colon cancer is about 1 in 18, meaning that by age 80, if you don’t get screened, that’s the likelihood you’re going to get cancer.”

Dr. MacMillan, president of the Massachusetts Gastroenterology Association and owner and president of Merrimack Valley Gastroenterology in Haverhill, appears on the May edition of Physician Focus with colleague Raj Devarajan, M.D., to discuss colorectal cancer and the importance of screening and prevention. Dr. Devarajan is the president of Middlesex Gastroenterology and Endoscopy Center in Acton and a board member of the Massachusetts Gastroenterology Association. Hosting this edition is primary care physician Bruce Karlin, M.D.

As gastroenterologists, physicians who take care of all parts of the gastrointestinal or digestive tract, the doctors deal with many types of cancers affecting such organs as the esophagus, stomach, and pancreas, but says Dr. MacMillan, “Colorectal cancer is by far much more prevalent than other cancers in the gastrointestinal tract.”

The cancer occurs in the colon and the rectum, parts of the large intestine, and is caused by growths called polyps that can turn into cancer.

The causes of colorectal cancer, the physicians say, result from an interplay of genetics, the environment, diet, and lifestyle.

“What’s really interesting,” says Dr. Devarajan. “is that there is such a high prevalence of colorectal cancer in westernized nations. In Asia, for example, the incidence is quite low, but immigrants to the U.S., after 10-12 years, have the same frequency of the disease as those born or living for a long time in the U.S.”

That suggests a link between colorectal cancer and environmental factors, particularly diet. Dr. Devarajan notes that a diet high in fat, low in fiber, with too much processed food and red meat, appears to have a link to colorectal cancer.

So what do the physicians advise their patients?

Screening should begin at age 50, the physicians say, but should occur earlier – at age 40 – if there is a family history of the disease. While various screening tests are available, the doctors strongly recommend colonoscopy, despite the extra time it may take and the potential annoyance of cleaning the colon, a necessary step to ensure a proper procedure.

“Colonoscopy is the best test out there,” says Dr. MacMillan. “It’s the test most likely to find something that can cause harm and it’s the only test that reduces personal risk.”

Adds Dr. Devarajan: “Colonoscopy is not just screening. This is a preventive test. We are actually preventing cancer. Polyps are the key. We want to remove the polyps because they can eventually become cancer.”

Watch the above video for more discussion, including conversation about other screening tests, guidelines for how often patients should get a colonoscopy, why cost is becoming a financial obstacle to getting screened, suggestions as to why colorectal cancer is affecting more and more young people, and the importance of the “prep” prior to the colonoscopy.

MMS/Richard Gulla

American Cancer Society

National Cancer Institute

American College of Gastroenterology

Centers for Disease Control

"Colorectal Cancer" PSA

Left to right: Bruce Karlin, M.D.; Francis P. MacMillan Jr., M.D., Raj Devarajan, M.D.
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