Major finding: In the community-based setting, surveillance colonoscopy is substantially overused for low-risk patients, but it is underused for those with advanced lesions, according to current guidelines.
Source of data: Subjects participating in a randomized, controlled trial of community-based cancer screening were interviewed. The participants had undergone flexible sigmoidoscopy at the time of randomization between 1993 and 2001. They had then undergone follow-up diagnostic colonoscopy within 18 months of that exam, and had been followed for at least 5 more years (median follow-up, 9 years), undergoing surveillance colonoscopy as recommended by their physicians.
Disclosures: This study was supported by the National Cancer Institute. The investigator reported no financial conflicts of interest.
In community practice, surveillance colonoscopy is substantially overused for low-risk patients, but it is underused for those with advanced lesions who need it most, Dr. Robert E. Schoen and his colleagues reported.
Interventions are needed to better align the use of surveillance colonoscopy with actual patient risk, they noted.
Survey results have suggested that primary care physicians, gastroenterologists, and surgeons all endorse surveillance colonoscopy at more frequent intervals than is recommended in guidelines.
However until now, “no studies have measured the actual use of surveillance colonoscopy on a community-wide basis, nor have they examined how surveillance is being employed in relation to prior histologic findings,” said Dr. Schoen of the University of Pittsburgh Cancer Institute and his associates.
The investigators assessed use of surveillance colonoscopy by interviewing 3,627 subjects participating in a randomized, controlled trial of community-based cancer screening. These subjects had undergone flexible sigmoidoscopy at nine regional study centers across the United States at the time of randomization between 1993 and 2001.
They had then undergone follow-up diagnostic colonoscopy within 18 months of that exam, and had been followed for at least 5 more years (median follow-up, 9 years), undergoing surveillance colonoscopy as recommended by their physicians.
The study subjects were aged 55–74 years at enrollment. In all, 60% were men, 93% were white, and nearly 70% had attended or graduated from college.
At the initial screening, 1,342 subjects had advanced adenoma, 1,022 had nonadvanced adenoma, and 1,263 had nonadenomatous findings.
Among the subjects who had no adenomas, 27% underwent surveillance colonoscopy within 5 years and 45% did so within 7 years.
A large subgroup of these subjects (70%) had no symptoms and no family history of colorectal cancer, nor had their exams been incomplete or inadequate. In other words, they had no identifiable reason for a repeat surveillance exam. Yet more than 35% of them underwent a second surveillance at a median of 3 years after the first.
Including the baseline exam, more than 90% of these subjects had three colonoscopies within a 9-year period. “This level of utilization contrasts to current guidelines, which advise that colonoscopy can be deferred for 10 years after an exam in which no adenoma is detected,” Dr. Schoen and his colleagues said.
The subjects with nonadvanced adenoma also overutilized surveillance colonoscopy. More than one-third of them had repeat exams within 4 years, when early guidelines had recommended a 5-year interval and more recent guidelines recommend a 5- to 10-year interval in such cases.
Almost all the repeat colonoscopies were performed by the same physician, by the same practice, or in the same location as the screening colonoscopy that categorized these subjects as low risk. This means that lack of communication among physicians was unlikely to be the reason for unnecessary overutilization, the investigators said.
In contrast with low-risk patients, only 31% of the subjects with advanced adenoma had a repeat colonoscopy within the recommended 3 years, and only 58% underwent surveillance within 5 years, according to the findings.
“Subjects with advanced adenoma are advised to undergo a surveillance exam within 3 years because of their increased risk for subsequent colorectal cancer, and the 3-year follow-up recommendation has been in place for many years,” the researchers noted.
It is unclear why so many of these high-risk subjects did not undergo surveillance as recommended.
In general, older patients were less likely than younger patients to have repeat colonoscopies, and Dr. Schoen and his associates initially speculated that perhaps they had a higher burden of comorbid conditions that rendered colon cancer less of a concern.
The findings from the investigation indicate that the costs of colonoscopy likely have been underestimated because estimates usually are based on “ideal” adherence to screening guidelines, and it appears that many patients undergo the procedure more often than recommended.