Patients with colorectal cancer associated with Lynch syndrome and MLH1 promoter hypermethylation have similar prognoses.

Haraldsdottir S1, Hampel H2, Wu C3, Weng DY4, Shields PG3, Frankel WL5, Pan X6, de la Chapelle A2,4,7, Goldberg RM3, Bekaii-Saab T3.

Author information

Abstract

PURPOSE:

Mismatch repair-deficient (dMMR) colorectal cancer (CRC) is caused by Lynch syndrome (LS) in 3% and sporadic inactivation of MLH1 by hypermethylation (MLH1-hm) in 12% of cases. It is not clear whether outcomes between LS-associated and MLH1-hm CRC differ. The objective of this study was to explore differences in clinical factors and outcomes in these two groups.

METHODS:

Patients with dMMR CRC identified by immunohistochemistry staining and treated at a single institution from 1998 to 2012 were included. MLH1-hm was established with BRAF mutational analysis or hypermethylation testing. Patients' charts were accessed for information on pathology, germ-line MMR mutation testing, and clinical course.

RESULTS:

A total of 143 patients had CRC associated with LS (37 patients, 26%) or MLH1-hm (106 patients, 74%). Patients with LS were younger, more often male, presented more often with stage III disease, and had more metachronous disease than patients with MLH1-hm tumors. There was no difference in cancer-specific survival (CSS) between the groups; overall survival was longer in patients with LS, but this difference was minimal after adjusting for age and stage at diagnosis.

CONCLUSION:

CSS did not differ in LS-associated CRC compared with MLH1-hm CRC, suggesting that they carry a similar prognosis.Genet Med advance online publication 11 February 2016Genetics in Medicine (2016); doi:10.1038/gim.2015.184.