Loss of hMLH1 expression correlates with improved survival in stage III-IV ovarian cancer patients.

Pre-clinical data suggest a relationship between DNA MisMatch Repair (MMR) system failure, particularly the inactivation of genes hMLH1 and hMSH2, and resistance to drugs like cisplatin and carboplatin. We studied the correlation between loss of hMLH1 expression in tumour cells and clinical outcome in 38 patients with ovarian cancer, who underwent cisplatin-based chemotherapy. 19 patients (56%) showed loss of hMLH1 expression (Group A) while 15 patients (44%) showed normal hMLH1 expression (Group B). 4 patients were not evaluable for hMLH1 expression. The 2 groups of patients were similar for clinical characteristics, response to chemotherapy and time to progression. Group A patients showed a median survival of 55 months whereas Group B patients had a median survival of 12 months (P=0.014). Loss of hMLH1 expression was the only independent predictor of survival in the multivariate analysis. Our observations suggest a relationship between loss of hMLH1 and improved survival in advanced ovarian cancer.