Fecal colorectal cancer tests effective over time

Reuters Health Information: Fecal colorectal cancer tests effective over time

Fecal colorectal cancer tests effective over time

Last Updated: 2016-01-25

By David Douglas

NEW YORK (Reuters Health) - The fecal immunochemical test (FIT) has shown efficacy over as many as four annual rounds of colorectal cancer (CRC) screening, according to a large retrospective study.

As Dr. Douglas A. Corley told Reuters Health by email, "There are two commonly used tests for colorectal cancer screening in the United States: colonoscopy and fecal immunochemical tests. Colonoscopy requires a bowel preparation to clean you out and is invasive but, if normal, it is done infrequently (every 10 years)."

He added, "FIT is simple to do at home but, to be most effective, needs to be done every year. This has the advantage of potentially picking up cancers that grow between tests. There are few studies that have looked at how well FIT picks up cancers when used year after year. Most studies only looked at one or two years of use for how well FIT-detected cancers. It is possible that the first year of use may 'clear out' most of the easily detectable cancers and that FIT might not work as well in subsequent years."

According to a January 25 online paper in Annals of Internal Medicine, Dr. Corley, of Kaiser Permanente Division of Research, Oakland, California, and colleagues invited more than 670,000 health plan members aged 50 to 70 to undergo FIT screening. Almost half (48.2%) participated in the first round. And 75.3% to 86.1% of those who remained eligible did so for subsequent rounds.

Median follow-up was for four years, and 32% of round one participants crossed over to endoscopy over four screening rounds.

The FIT positivity rate (5.0%) and positive predictive values (adenoma, 51.5%; CRC, 3.4%) were highest in the first round. Overall, FIT detected 80.4% of patients with CRC diagnosed within one year of testing, including 84.5% in round one and 73.4% to 78.0% in subsequent rounds.

Summing up, Dr. Corley said, "We found that the sensitivity was highest in the first year, likely from clearing out cancers that were there for a while and easily detected, but that in subsequent years the sensitivity, though 5% to 10% lower, remained high. Also, most people who started with FIT continued doing it, suggesting that it is both feasible and effective for colorectal cancer screening."

He noted that effective tests for colorectal cancer screening "have different strengths and weaknesses. This study provides additional support that FIT can be an important tool for getting more people screened in a way that is both sensitive to picking up cancers and that people can comply with."

Commenting on the findings by email, Dr. Peter S. Liang told Reuters Health, "This study demonstrates that FIT is a good screening test for colorectal cancer when done on a yearly basis."

Dr. Liang, of the Division of Gastroenterology at New York University Manhattan Veterans Administration Hospital, added, "Given that less than half of the people who were initially invited actually participated and an additional 15% to 25% did not complete screening at each successive round, it also shows that we need to increase screening rates and maintain it at a high level to get the maximum protective effect of the test."

The National Cancer Institute partially supported this research. Two coauthors reported disclosures.

SOURCE: http://bit.ly/20pveyK

Ann Intern Med 2016.

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