The Colon Cancer Screening Controversy: How Old is Too Old to Screen?

A recent study in the Archives of Internal Medicine found 57 percent of seniors age 75-79 had been screened for colon cancer despite the increased risks and limited benefit. The study was followed by calls to set upper age limits for colon cancer screening.

However, Andrew Spiegel, CEO of the Colon Cancer Alliance, says older patients should still be screened for colon cancer because the average age at diagnosis is 71, and 43 percent of cases are diagnosed at age 75 and older.

"I think not screening patients over the age of 75 is a really bad idea when the average age at diagnosis is 71," he says. "We are living in a world now where people are living much, much longer. Why would you stop screening at 75?"

One of the reasons Mr. Spiegel recommends screening be done for elderly patients is that colon cancer is the one major cancer that can be prevented — and the prevention method is the screening test, he says. Removing polyps during a colonoscopy prevents colon cancer. Even so, an estimated 50,000 people die every year of colorectal cancer in the U.S. About 1 in 20 Americans will get colorectal cancer.

"The thing that is so frustrating about all of those numbers is that it's an almost entirely preventable disease," he says. "You can almost certainly avoid this disease if you screen for it. If people would just get screened, you can remove polyps before they develop into cancer. The other issue on the screening side is deciding when people should be screened. If you're going to catch this cancer, you want to catch it in the earliest stages when it is far more treatable."

The Colon Cancer Alliance conducted a survey in collaboration with Quest Diagnostics earlier this year to determine colon cancer screening rates as well as interest in a blood test for colon cancer. Mr. Spiegel was surprised by the high rate of screening. Usually, he says, studies find a screening rate in the 50 percentile, but this survey found a rate of 69 percent among people age 50 and over.

"That, to me, was really startling data," he says. "People are getting the message and are finally getting screened. A year ago, the CDC conducted a similar survey and found screening rates were about 65 percent, so we do see progress."

However, the survey also found nearly one-quarter of patients over the age of 75 had never been screened for colon cancer. The same percentage of patients age 60-70 had never been screened, while 30 percent of those age 55-64 and 47 percent of patients age 50-54 had never been screened.

Although the benefits decrease and risks increase as the invasive colonoscopy procedure is performed on older patients, Mr. Spiegel and other researchers recommend screenings for patients over the age of 75.

The current recommendations for cancer screenings vary. While the U.S. Preventive Services Task Force recommends against routine colon cancer screening of people over age 75, the American Cancer Society offers no age limit for colon cancer screenings but says men with a life expectancy of less than 10 years should not be screened for prostate cancer.

At Digestive Disease Week 2011, Ann G. Zauber, MD, principal investigator of the National Colonoscopy Study and associate attending biostatistician at the Memorial Sloan-Kettering Cancer Center in New York City, presented a model that simulated colon cancer screening in patients older that 75 who had never been screened. Based on the findings, she concluded that patients should be screened until the age of 85 depending on risks and benefits for specific patients.

Dr. Zauber also used this model to determine the life-years gained by screening different age groups. She found 155 total life-years gained for all patients screened at 65 years, 132 at 70 years, 108 at 75 years, 57 at 80 years, 27 at 85 years and 6.5 at 90 years. That works out to be one month gained per person screened at age 75 and only 1.5 days gained per person screened at age 91.

Another study presented at DDW 2011 found that the incidence of colorectal cancer in patients over the age of 75 is high enough to necessitate screening. Vishnu Naravadi, MD, and colleagues reviewed charts of patients undergoing colonoscopy at Mt. Sinai Hospital in Chicago between 2007 and 2010. Adenomas were detected in 58.9 percent of males and 27.5 percent of females, and significant colorectal tumor was detected in 23 percent of males and 17.2 percent of females. No adverse events were reported.

Although colonoscopy is considered the "gold standard" for colon cancer screening, blood tests, including one in development by Quest Diagnostics, can also screen for colon cancer, although they won't be able to prevent the disease by detecting or removing polyps. In the same Colon Cancer Alliance and Quest survey, 78 percent of respondents said they would be likely to take a blood test for colon cancer if it were available.

Mr. Spiegel refrains from recommending one screening method over another because "the best test for colon cancer screening is the one the patient gets."

Related Articles on Colorectal Cancer:
Roper St. Francis Healthcare First in South Carolina to Use da Vinci robot With Firefly Fluorescence Imaging in Colon Cancer Surgery
Dr. Peter Apicella: Colon Cancer Detection Improved With Virtual CT Colonoscopy
Obese Patients Less Likely to Have Genetic Mutation Associated With Better Colorectal Cancer Outcomes

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