Excision repair cross complementation group 1 and thymidylate synthase expression in patients with mesothelioma

Background: We hypothesized that in patients with malignant pleural mesothelioma (MPM) undergoing extrapleural pneumonectomy (EPP), high expression of excision repair cross complementation group 1 (ERCC1) and low expression of thymidylate synthase (TS) are associated with prolonged survival. Patients and Methods: Consecutive patients undergoing EPP at our institutions were reviewed. Tissue microarrays were constructed using five 1-mm cores per patient. TS and ERCC1 protein expression was evaluated by immunohistochemical techniques. The average percentage scores from evaluable cores were assessed and the median score was used to divide the group. Overall survival (OS) from the time of surgery was determined by the Kaplan-Meier method and results were compared by the log-rank test. Results: Eighty patients were included: median age, 58 years; 79% men; 76% epithelial and 24% biphasic subtypes; 25% and pathologic stage I/II and 73% stage III/IV. The median OS was 18.2 months (80% deceased at the censor date). Nineteen patients received neoadjuvant chemotherapy; 2 patients received chemotherapy with adjuvant intent and 28 patients received palliative chemotherapy. The median score was 10.2% for TS and 35% for ERCC1. There was no correlation between TS expression and OS (13.7 vs. 21.6 months for low and high levels, respectively; P =.32). There was a trend between high ERCC1 expression and longer OS (27.6 vs. 10.3 months; P =.06). Conclusion: In this series of patients with MPM undergoing EPP, TS expression was not associated with prolonged survival, but there was a trend for longer survival in patients with high ERCC1 expression.