Colonoscopy timing after positive fecal test linked to colorectal cancer risk
A follow-up colonoscopy more than 10 months after a positive FIT result is associated with a higher risk of colorectal cancer.
In patients with a positive fecal immunochemical test (FIT) result, a follow-up colonoscopy after 10 months was associated with a higher risk of colorectal cancer and more advanced-stage disease at the time of diagnosis compared with a follow-up colonoscopy at 8 to 30 days, researchers reported in JAMA.
Douglas A. Corley, MD, PhD, from the Kaiser Permanente Division of Research in Oakland, California, and colleagues conducted a retrospective cohort study from January 1, 2010, to December 31, 2014, within Kaiser Permanente Northern and Southern California. A total of 70,124 patients between 50 and 70 years of age (median age, 61; men, 52.7%), were eligible for colorectal cancer screening with a positive FIT result who had a follow-up colonoscopy.
The main outcome was the risk of any colorectal cancer and advanced-stage disease, which was defined as stage III and IV cancer. Odds ratios (ORs) were adjusted for patient demographics and baseline risk factors.
A total of 2,191 cases of any colorectal cancer and 601 cases of advanced-stage disease were diagnosed. Compared with colonoscopy follow-up within 8 to 30 days (n=27,176), no significant differences were observed between follow-up at 2 months (n=24,644), 3 months (n=8,666), 4 to 6 months (n=5,251), or 7 to 9 months (n=1,335) for risk of any colorectal cancer (cases per 1,000 patients: 8 to 30 days, 30; 2 months, 28; 3 months, 31; 4 to 6 months, 31; and 7 to 9 months, 43) or advanced-stage disease (cases per 1,000 patients: 8 to 30 days, 8; 2 months, 7; 3 months, 7; 4 to 6 months, 9; and 7 to 9 months, 13), according to the investigators.
The risks were significantly higher for examinations conducted at 10 to 12 months (n=748) for any colorectal cancer (OR, 1.48; 49 cases per 1,000 patients) and advanced-stage disease (OR, 1.97; 19 cases per 1,000 patients) and more than 12 months (n=747) for any colorectal cancer (OR, 2.25; 76 cases per 1,000 patients) and advanced-stage disease (OR, 3.22; 31 cases per 1,000 patients).
“Longer intervals could increase the chance of neoplastic progression, whereas short intervals may substantially increase patient and clinician burdens without benefiting cancer outcomes,” stated Dr Corley and colleagues. “In the current study, nearly 75% of patients with a positive FIT result received a colonoscopy within 90 days. This required rapid communication of positive results to patients and physicians, sufficient colonoscopy access, rapid scheduling, and tracking of examination completion. However, even with one of the most rapid follow-up rates reported to date, only one-third of patients with a positive FIT result received a follow-up colonoscopy within 30 days.”
In a related editorial, Carolyn M. Rutter, PhD, from RAND Corporation in Santa Monica, California, and John M. Inadomi, MD, from the University of Washington School of Medicine in Seattle, commented on the study's findings.
“The study by Corley et al provides important reassurance for patients and physicians,” Drs Rutter and Inadomi wrote. “The findings indicate that there is no immediate need to rush to have a colonoscopy after a positive FIT result, reflecting the clinical understanding that colorectal cancer is a disease that generally develops slowly. Longer time to follow-up will reduce the benefit of FIT, with detection of more cancers and more late-stage disease. The clinically relevant questions include the magnitude of benefit reduction and the duration of the ‘safe window' until colonoscopy for which maximal benefit is still achieved.
“For most patients with a positive FIT screening result, sooner is probably better for follow-up colonoscopy because cancer risk increases over time, but increases slowly,” Drs Rutter and Inadomi continued. “Practically, an important reason for a shorter interval for follow-up colonoscopy is a reduction in the risk of losing contact with patients.”
- Corley DA, Jensen CD, Quinn VP, et al. Association between time to colonoscopy after a positive fecal test result and risk of colorectal cancer and cancer stage at diagnosis. JAMA. 2017;317(16):1631-1641. doi: 10.1001/jama.2017.3634
- Rutter CM, Inadomi JM. Follow-up of positive fecal test results: sooner is better, but how much better? JAMA. 2017;317(16):1627-1628. doi: 10.1001/jama.2017.3629