Different surgical outcome and follow-up status between dMMR and pMMR colorectal cancer patients who fulfilled with Amsterdam-II criteria

Background: Although hereditary non-polyposis colorectal cancer (HNPCC) could be subtyped into proficient or deficient mismatch repair gene expression (pMMR or dMMR), distinct clinical features between these two subgroups patients were rarely reported. Methods: We retrospectively analyzed 175 hereditary non-polyposis colorectal cancer (HNPCC) patients between January 1995 and December 2012. Cox proportional hazards model was used to compare the differences between two subgroups. Results: Significant differences of disease free survival (DFS) and overall survival (OS) exist between dMMR and pMMR. In addition to other factors including younger mean age of diagnosis for dMMR patients (48.6 years vs. 54.3 years), operation type (more extended colectomy for dMMR 35.8% vs. 14.5%), tumor location (right colon predominance for dMMR 61.7% vs. 27.3% and more rectum cases for pMMR 41.8% vs. 11.7%), tumor differentiation (more poor differentiation for dMMR 23.3% vs. 9.0%), N staging (more N0 cases for dMMR 70.8% vs. 50.9%), more frequently presence of extra-colonic tumors for dMMR (16.7% vs.1.8%), and lower recurrence rates (9.1% vs.35.3%). Significantly different cumulative incidences of developing metachronous colorectal cancer were observed with 6.18 for pMMR patients and 20.57 person-years for dMMR patients (p < 0.001). Conclusions: Distinct clinicopathological features significantly exist between dMMR and pMMR subtypes patient, MMR status should be consider to tailor operation types and follow up surveillance between these two subgroups patients who all fulfilled with Amsterdam-II criteria.