Screening May Have Prevented A Half-Million Cases Of Colon Cancer

Issue 24 Winter/Spring 2015

U.S. data from 1987-2009 shows cancer incidence fell as use of colonoscopy rose

Picture of a colonoscopy

It's a true cancer prevention success story: A new study finds that more than a half a million cases of colorectal cancer may have been prevented over the past 30 years in the United States due to better screening.

"These numbers represent real patients and families who have been spared the trauma of a cancer diagnosis and treatment," study senior author Dr. James Yu, of the Yale School of Medicine, said in a university news release.

As the second leading cancer killer, colon cancer still claims more than 50,000 lives in the United States each year. However, tests such as fecal occult blood testing, sigmoidoscopy and colonoscopy are highly effective in spotting suspicious polyps in the colon and effecting their removal before cancer can start or spread.

More and more Americans appear to be getting that message. The new study, published earlier this year in Cancer, tracked data on colon cancer screening from the U.S. National Cancer Institute's Surveillance, Epidemiology and End Results database as well as its Cancer Trends Progress Report.

The Yale team found that the percentage of adults age 50 or older who underwent colorectal cancer screening kept rising, year by year — from about 35 percent in 1987 to more than 66 percent by 2009.

At the same time, the incidence of late stage colorectal cancers began to fall – from about 118 cases per 100,000 people over the age of 50 in 1987 to 74 cases per 100,000 by 2009.

In fact, "we estimate that between 236,000 and 550,000 colorectal cancers were prevented during [this] era of increasing colorectal cancer screening," the Yale researchers conclude. Most of this was due to screening's ability to catch precancerous or cancerous lesions before they had time to progress to late-stage disease.

The study authors do not discount the potential role of other factors – including the rise in the use of NSAID painkillers such as aspirin – in bringing down the incidence of colon cancer. However, the study does seem to affirm the central role of colonoscopy and other screening methods in that decline, the researchers said.

And while controversy swirls around the effectiveness of screening for breast and prostate cancer, colon cancer screening "appears largely to have avoided the pitfalls of over-diagnosis," Yu's group noted.

"The efficacy of colorectal cancer screening is important to highlight, especially at a time when there has been a national discussion about screening for other types of cancers," said study co-author Dr. Cary Gross, director of the Yale COPPER Center.

Yu agreed. Based on the numbers, he described colorectal cancer screening as "one of the major successes in cancer care."