Screening can detect cancer at an earlier stage before it becomes symptomatic, and the detection and removal of colorectal lesions can prevent cancer. Several screening tests can be used to find polyps or colorectal cancer. The fecal immunochemical test (FIT) uses antibodies to detect blood in the stool. For positive test results, a follow-up colonoscopy is recommended.1
Results recently published in JAMA, Corley et al explored the timing of follow-up colonoscopy after a positive fecal immunochemical test and the increased risk of colorectal cancer.2
This retrospective cohort study (2010–2014) within Kaiser Permanente Northern and Southern California, involved 70,124 patients aged 50 through 70 years with a positive FIT result. The authors examined the relationship between time (days) to colonoscopy after a positive FIT result and risk of any colorectal cancer and advanced-stage disease. Of these patients with positive FIT results, there were 2,191 cases of any colorectal cancer and 601 cases of advanced-stage disease diagnosed. Compared with colonoscopy follow-up within 8 to 30 days (n = 27,176), there were no significant differences 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 1000 patients: 8–30 days, 30; 2 months, 28; 3 months, 31; 4–6 months , 31; and 7–9 months, 43.
For advanced-stage disease cases per 1000 patients: 8-30 days, 8; 2months, 7; 3 months, 7; 4–6 months, 9; and 7–9 months, 13.
Risks were significantly higher for examinations at 10 to 12 months for any colorectal cancer (49 cases per 1000 patients and advanced-stage disease (19 cases per 1000 patients. For examinations after 12 months (n = 747) for any colorectal cancer were 76 cases per 1000 patients and advanced-stage disease were 31 cases per 1000 patients.
Among patients with a positive fecal immunochemical test result, compared with follow-up colonoscopy at 8 to 30 days, follow-up after 10 months was associated with a higher risk of cancer and more advanced-stage disease at the time of diagnosis. Further research is needed to assess whether this relationship is causal. Could other factors be influencing the results?
Colonoscopy is the most commonly used colorectal cancer screening test, but it is invasive, can be inconvenient, and also costly. The FIT can provide screening to more patients, but requires follow-up colonoscopy for patients with positive test results.
What strategies can be implemented to encourage patient adherence to follow-up testing recommendations?
- Centers for Disease Control and Prevention. Colorectal Cancer Screening Tests. 2017 Mar 24.
- 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 Apr 25;317(16):1631-1641.