Colon cancer screening rates vary widely across U.S.

(Reuters Health) - The proportion of U.S. adults who get recommended colon cancer screenings has never been as high as doctors would like, but a new study suggests that it’s much lower than expected in some pockets of the country.

To catch colon cancer early, when it’s easier to treat and less lethal, physicians typically recommend that adults aged 50 to 75 get screened every 10 years with a colonoscopy or annually with fecal tests. Nationwide, only about 67 percent of adults in this age range were current with screening, the study found.

At the state level, screening rates ranged from a low of 59 percent in Wyoming to a high of 75 percent in Massachusetts.

Researchers found even greater variability within some states. Screening rates were lowest in one county in Alaska, at just 40 percent, and highest in one county in Florida, at 80 percent.

The widest gap among counties was in South Dakota, with a 29-percentage point difference between the counties with the lowest and highest screening rates; the smallest gap was in Connecticut, with about 4 percentage points separating the counties with the highest and lowest screening rates.

“We anticipated variations by county in colorectal cancer screening within the states because of different educational and income levels and geographical inequalities, but we were still struck by differences of more than 20 percentage points between counties in some states,” said lead study author Zahava Berkowitz, of the National Center for Chronic Disease Prevention and Health Promotion, at the U.S. Centers for Disease Control and Prevention in Atlanta.

“Although most providers recommend colonoscopy, some people refuse to undergo the preparation for the procedure and/or are afraid of an invasive procedure,” Berkowitz said by email. “Therefore, it is important that multiple screening options are offered to match patients’ preferences.”

The most common screening method is a colonoscopy exam that snakes a tiny camera through the rectum to view the colon to search for abnormal tissue growth. Patients may need to use laxatives or an enema to empty the bowels before the exam, and sedation is usually required during the procedures.

An alternative is fecal occult blood testing (FOBT), which looks for blood - a possible sign of cancer - in stool samples. Another option involves doing FOBT every three years along with a sigmoidoscopy exam of just the lower colon every five years.

The U.S. Preventive Services Task Force, a government-backed independent panel that assesses the evidence for medical procedures, recommends using any of these methods starting at age 50 for adults who don’t have inflammatory bowel disease or a family history of colon cancer. People with those extra risk factors or other specific conditions may need earlier or more intensive screening.

For the current study, researchers modeled county level screening rates by using CDC survey data for 251,360 adults aged 50 to 75 and looking at U.S. population estimates for 3,142 counties nationwide.

Screening varied by ethnicity, with about 69 percent of white adults current on recommended screenings, compared with 57 percent of Hispanics, the study found.

One limitation of the study is that researchers relied on survey participants to accurately recall and report their screening exams, and inaccurate responses might throw off the estimated screening rates, researchers note in Cancer, Epidemiology, Biomarkers and Prevention.

The study also doesn’t offer insight into why so many people are not current with their recommended screenings, and there are many factors that can contribute to this, said Electra Paskett, a cancer researcher at Ohio State University in Columbus who wasn’t involved in the study.

Screening rates tend to be lowest in places that don’t have polices to cover these tests for everyone or don’t have providers in the community who can do the tests, Paskett said by email. Doctors also might not recommend screening, or people might not want it or want to travel too far to get it.

“All of these act and interact in different ways to keep people from screening,” Paskett added. “It matters because colorectal cancer is totally preventable as is death from colorectal cancer if people get screened regularly.”

SOURCE: Cancer, Epidemiology, Biomarkers and Prevention, online March 1, 2018.