Dear Doctor: I'm 47 years old and was very happy to have three more years before my doctor started bugging me about a colonoscopy. But my husband says there are new guidelines, and I'm now actually two years late! Why the changes?
Dear Reader: Your husband is correct -- the American Cancer Society recently updated its screening guidelines for colorectal cancer. Rather than wait until age 50, it now recommends people at average risk for the disease should begin regular screenings at age 45. The organization cites the recent rise of colorectal cancer among young people as the impetus for the change. As of yet, neither the United States Preventive Services Task Force nor the American College of Gastroenterology has adopted the new guidelines.
According to a study published last year in the Journal of the National Cancer Institute, the proportion of rectal cancer diagnosed in adults younger than the age of 55 doubled from 1990 to 2013. That means nearly one-third of all diagnoses of rectal cancer now occur among people 55 and younger. Meanwhile, rates of rectal cancer for adults over the age of 55 are continuing their 40-year decline.
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Researchers looking into this demographic shift are questioning whether the same lifestyle factors that appear to have a hand in the ongoing obesity epidemic are at work when it comes to the spike of colorectal cancers among younger adults. That is, a sedentary lifestyle, diets that are high in fat and low in fiber, an increase in the consumption of sugar and of highly processed foods, and the weight gain that accompanies these behaviors.
Although colorectal cancer is the fourth most-common cancer diagnosed among adults in the U.S., it is the second-leading cause of cancer death. That's frustrating because colon and rectal cancers are highly curable when caught early. The five-year relative survival rate for people with stage 1 rectal cancer is about 87 percent, according to statistics compiled by the American Cancer Society. For stage 1 colon cancer, that number jumps to 92 percent. Once colorectal cancers spread to other parts of the body, however, they become significantly harder to treat. Metastatic, or stage 4, colon cancers have a five-year relative survival rate of 11 percent. For stage 4 rectal cancers, it's 12 percent.
Catching these cancers early requires regular screening. That's because, in their early stages, colorectal cancers tend to be asymptomatic. Most begin as a growth in the inner surface of the colon or rectum. The majority of these growths, known as polyps, are not malignant. However, certain types of polyps, known as adenomas, have a higher risk of becoming cancers. And that's where the colonoscopy becomes important. Using a flexible tube with a tiny camera, a doctor can scan the interior of the colon to identify potential abnormalities. He or she may also collect tissue samples for biopsy and remove polyps. Stool-based lab tests and special CT scans are also effective.