麻豆传媒

WASHINGTON -- Screening recommendations for individuals who have a family history of young-onset colorectal cancer need to be improved and more consistently implemented, and aggressive follow-up should be provided to limit the current increase in colorectal cancer in individuals ages 40 to 49, a retrospective case-control study suggested.

Among 2,473 cases of young-onset colorectal cancer enrolled from 1998 to 2007 in the multisite Colon Cancer Family Registry, the early screening criteria from the American Cancer Society (ACS) were met by only 25% and not met by 75%, according to Samir Gupta, MD, of the University of California San Diego.

And even for those who did meet the criteria, 98% could have had their cancers diagnosed earlier -- or even prevented -- if early screening criteria had been fully implemented, he said during a presentation at Digestive Disease Week.

Approximately 10% of cases of colorectal cancer in the U.S. occur in individuals age <50, most often between ages 40 and 50. Currently, the primary strategy for early detection is based on family history guidelines. The recommends that screening be initiated at age 40 for individuals with one or more first degree relatives who had colorectal cancer or for those with two or more second degree relatives. Colonoscopy also is recommended every 5 years beginning 10 years prior to the age at which a first degree relative received the diagnosis.

However, few data are available to support the effectiveness of those recommendations. Accordingly, Gupta's group aimed to examine the sensitivity and specificity of the current guidelines, and to compare the observed age of diagnosis among cases with the age at which screening initiation would have been indicated based on family history. The analysis included cases enrolled between 1999 and 2007 in the colon cancer family registry, which includes more than 42,000 participants from more than 15,000 affected families.

The 2,473 cases they identified were compared with 772 controls. Mean age was 45, and slightly more than half were women. Among cases, 37% had a family history of colorectal cancer, whereas for controls, the number was 17%. Also among cases, 17% had a first-degree relative with the disease as did 8% of controls, and 17% had at least one second degree relative as did 9% of controls.

The ACS screening criteria were met by 25% of cases and by 10% of controls, which represented a sensitivity of only 25% but a specificity of 90%.

Among the 614 cases who did meet the criteria for early screening, just 2% would have been recommended for screening initiation at the same age or older than their actual age at diagnosis.

"We noticed an interesting pattern with respect to the proportion of colorectal cancer cases who were diagnosed at the same age as their first degree relative, which ranged from 34% to 55%," Gupta said. Overall, 44% of colorectal cancer cases were diagnosed at the same age as their youngest first degree relative with colorectal cancer.

"We speculate that this may suggest a possible approach where individuals could alert providers about their family history when reaching the same age as their affected relative. So a 44- or 45-year-old man could tell his provider that his father had been diagnosed at 45, and screening would then be undertaken," he said.

"We think these findings have important implications. First, we need improved application and follow-up of current family history-based guidelines, and if someone meets any of the criteria we really need to be very aggressive about trying to get them in because it could be an opportunity for early detection and prevention," he said.

"And then, because of the deficient sensitivity of current guidelines, we need novel strategies to identify patients at increased risk for colorectal cancer, including lifestyle and environmental approaches as well as genetic factors," he concluded.

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