Association Between Time to Colonoscopy After Positive Fecal Testing and Colorectal Cancer Outcomes: A Systematic Review

BACKGROUND & AIMS: Colonoscopy is required following a positive fecal screening test for colorectal cancer (CRC). It remains unclear to what extent time to colonoscopy is associated with CRC-related outcomes. We performed a systematic review to elucidate this relationship. METHODS: An electronic search was performed through April 2020 for studies reporting associations between time from positive fecal testing to colonoscopy and outcomes including CRC incidence (primary outcome), CRC stage at diagnosis, and/or CRC-specific mortality. Our primary objective was to quantify these relationships following positive fecal immunochemical testing (FIT). Two authors independently performed screening, abstraction, and risk of bias assessments. RESULTS: From 1,612 initial studies, 8 were included in the systematic review, with 5 reporting outcomes for FIT. Although meta-analysis was not possible, consistent trends between longer time delays and worse outcomes were apparent in all studies. Colonoscopy performed beyond 9 months from positive FIT compared to within 1 month was significantly associated with a higher incidence of CRC, with adjusted odds ratios (AORs) of 1.75 and 1.48 in the two largest studies. These studies also reported significant associations between colonoscopy performed beyond 9 months and higher incidence of advanced stage CRC (stage III or IV) at diagnosis, with AORs of 2.79 and 1.55, respectively. CONCLUSIONS: Colonoscopy for positive FIT should not be delayed beyond 9 months. Given the additional time required for urgent referrals and surgical planning for CRC, colonoscopy should ideally be performed well in advance of 9 months following a positive FIT.