BETTER SURVIVAL RATES IN PATIENTS WITH MLH1-ASSOCIATED HEREDITARY COLORECTAL-CANCER

Background & Aims: Patients with hereditary nonpolyposis colorectal ca ncer (HNPCC) have been suggested to have a better prognosis than patie nts with common sporadic colorectal cancer. However, the evidence has not been convincing. The aim of this population-based study was to com pare the survival rates of 175 patients with HNPCC with those of 14,00 0 patients with sporadic colorectal cancer diagnosed at <65 years of a ge in Finland from 1953 to 1993, Methods: The recent progress in molec ular genetics of hereditary colorectal cancer was utilized for the fir st time. One hundred twenty of the patients with HNPCC came from famil ies segregating a germline mutation in the MLH1 cancer predisposition gene. Results: The overall 5-year cumulative relative survival rate wa s 65% for patients with HNPCC and 44% for patients with sporadic color ectal cancer. The relative survival rates of patients with HNPCC were better in every strata analyzed. Conclusions: MLH1-associated colorect al cancer has a natural history different from that of common sporadic colorectal cancer. The better survival rates may be caused by the hea vy mutation burden affecting mismatch repair deficient tumor cells.