Background: Colorectal cancer (CRC) family history is a known risk factor for CRC development; however, effects of CRC family history on survival after CRC diagnosis are less well-defined. Our population-based analysis investigates whether familial CRC cases exhibit improved survival compared with sporadic CRC cases.
Methods: Cases enrolled in the University of California Irvine Gene-Environment Study of Familial Colorectal Cancer from 1994 to 1996 were analyzed, with follow-up through December 2006. Cases were categorized as familial or sporadic based on self-reported CRC family history in a first-degree relative. Univariate and multivariate survival analyses with Cox proportional hazards ratios were done for overall survival (OS) and CRC-SS (CRC-SS).
Results: One thousand one hundred fifty-four CRC cases were analyzed, including 781 colon cancer and 373 rectal cancer cases. Nineteen percent of colon cases had family history of CRC in a first-degree relative, compared with 16% of rectal cancer cases. No statistically significant differences between familial and sporadic colon or rectal cancer cases were detected for age, gender, ethnicity, stage, tumor location, histology, tumor grade, or stage-specific treatment rendered. Among colon cancer cases, family history of CRC (versus no family history as a reference group) was associated with improved OS (adjusted hazard ratio, 0.760; 95% confidence interval, 0.580-0.997), but not with CRC-SS (hazard ratio, 0.880; 95% confidence interval, 0.621-1.246). No OS or CRC-SS differences were detected for rectal cancer cases.
Conclusions: CRC cases with family history of the disease have improved overall survival compared with sporadic CRC cases, a finding that is independent of other relevant clinical factors.