Relative Risk
Search
Search

By Erik Ness

Relative Risk

Why are so many people with a family history of colorectal cancer not getting screened?

By Erik Ness


Colorectal cancer has become a big piece of the puzzle for researchers investigating why a higher percentage of African-Americans die of cancer than white men and women. One quarter of the difference in cancer death rates between white women and African-American women in the U.S. is due to the African-American women’s higher mortality rates from colorectal cancer; for men, it’s a more modest but still worrisome 11 percent. In fact, a task force of the American College of Gastroenterology argued in 2005 that the higher incidence and earlier age of diagnosis of colorectal cancer in African-Americans warranted screening beginning at age 45, not 50, the age recommended by the American Cancer Society for Americans at average risk of the disease.

But the challenge appears to be making screening happen at all. Research published in the March 24 Archives of Internal Medicine found that African-Americans are far less likely to undergo colonoscopy screening than whites, even when there is a family history of colorectal cancer. The most common reason for not getting screened, among both whites and African-Americans, was that a doctor had never suggested it.

The study examined more than 41,000 participants from the Southern Community Cohort Study, long-term research that began in 2002 and aims to follow about 90,000 people age 40 to 79 in 12 southern states. Two-thirds of the participants are African-Americans, who are over-represented in the study compared with the general population specifically to tease out disparities. More than half are being recruited from community health centers.

Screening dynamics for colon cancer in the population at large and among those carrying high-risk mutations are well-understood. What intrigued Harvey Murff, the lead researcher on the study, was that screening among those who are at higher risk due to cancer in their families was not as well-understood. Having a first-degree relative with colorectal cancer increases risk of developing the disease two to three times. These high-risk individuals are also more likely to be diagnosed with a malignancy 10 years earlier than those without a family history. “A sizable population—5 percent to 10 percent—would have a family history of colon cancer that would put them at significantly increased risk,” explains Murff, an internist and epidemiologist at the Vanderbilt University School of Medicine in Nashville, Tenn. And increased risk combined with lower screening rates would definitely have an impact on mortality and incidence.

Among those with more than one first-degree relative diagnosed with colon cancer, or with one first-degree relative diagnosed before turning 50, just 34 percent of whites reported being screened in the last five years. But an even lower number—21 percent—of African-Americans reported being screened. “Is family history motivating certain populations more than others?” wonders Murff. “There could be cultural differences in how people might perceive their risk related to family history. You have to have some cultural sensitivity to family history.”

There are still disparities in care and potential biological differences in colorectal cancer for which screening doesn’t account, but screening is a strong tool in prevention efforts. Michael Pignone, a general internist and epidemiologist at the University of North Carolina in Chapel Hill, has helped develop methods to improve outreach and education for both individual patients and organizations such as African-American churches. “I hope that better recognition of this disparity can be a step to remedying it,” he says. “We need more detailed interviews with African-American and white patients (and providers) to determine what is going wrong. Was [colorectal cancer] screening discussed at all? Are the patients aware of their risk? Would they have a test if recommended? Do providers believe that patients are not interested and thus do not ask them to be screened? Determining if there are differences between races at this level would be helpful to better understand how disparities emerge.”

One finding of the new study—that only 57 percent of high-risk white patients over 50 had been screened with colonoscopy—suggests “major quality gaps for all patients,” adds Pignone.

“Sometimes doctors don’t realize that what they advise somebody to do is not just going into one ear and coming out the other,” says Murff. “People listen. Doctors just need to be reminded of the importance of recommending these [tests] to their patients.”