Survival in familial colorectal cancer: a Danish cohort study

The monogenic Lynch syndrome (LS) is associated with better survival in colorectal cancer (CRC) patients. Whether family history of CRC affects CRC prognosis in general remains unclear. We evaluated overall mortality in a Danish cohort of CRC patients comparing patients with a family history (FHpos) to those without (FHneg) with focus on patients from non-syndromic families, thus FHpos patients were further divided into a non-syndromic group (FHNS) and a HNPCC/LS group (FHHNPCC). We included CRC patients diagnosed 1995-1998. First degree relatives were identified using Danish population registries and family history was obtained by linkage to Danish medical registries. 1- and 5-year mortality were evaluated using the Kaplan-Meier method and Cox regression, with adjustment for age, sex, cancer site, cancer stage, and comorbidity. 1196 CRC patients were included in the study, 219 FHpos patients of whom 197 were FHNS patients. 1- and 5-year adjusted Mortality Rate Ratios comparing FHpos patients to FHneg patients were 0.99 (95% CI 0.69, 1.42) and 1.07 (95% CI 0.87, 1.32), respectively. For FHNS patients, the corresponding MRRs were 1.01 (95% CI 0.69, 1.47) and 1.15 (95% CI 0.93, 1.43). For the FHHNPCC patients MRRs were 0.84 (95% CI 0.29, 2.44) and 0.66 (95% CI 0.33, 1.31), respectively. In contrast to the lower mortality in LS patients, other types of familial CRC do not seem to affect the survival after CRC diagnosis.