Introduction: Colon cancers diagnosed in the interval after a complete colonoscopy may occur due to limitations of colonoscopy or due to rapid tumor growth. The aim of this study was to compare the association of BRAF V600E mutation in interval versus non-interval colorectal cancers and to determine the relationship between BRAF mutation and 5-year survival.
Methods: We searched our institution's cancer registry for interval cancers, defined as colon cancers that developed within 5 years of a complete colonoscopy. These were frequency matched to patients with non-interval cancers. Archived cancer specimens were tested for BRAF V600E mutation and MSI.
Results: There were 63 interval and 131 non-interval cancers. BRAF mutation was present in 28% of interval cancers compared to 19% of non-interval cancers (P = 0.18). In a multivariable logistic regression model, proximal location (OR 1.85; 95% CI 1.01-3.8) and MSI (OR 2.7; 95% 1.1-6.8) were independently associated with interval cancers while BRAF mutation was not (OR 0.93; 95% CI 0.36-2.38). BRAF mutation portended a poor 5-year survival, particularly among microsatellite stable cancers.
Conclusions: BRAF mutation is not associated with interval cancers but is a marker of poor prognosis, particularly in microsatellite stable cancers.