Treatment and survival analyses of malignant mesothelioma in Japan

There are few reports concerning treatment strategies and their contributions to survival of patients with malignant mesothelioma (MM) in Japan.

We extracted all death cases due to MM between 2003 and 2008. The diagnosis of MM was confirmed in 929 cases. Histological subtypes was determined in 709 cases, including 396 (55.9%) epithelioid, 154 (21.7%) sarcomatoid, 126 (17.8%) biphasic, and 33 (4.7%) other types.

Median overall survival (OS) of all MM cases was 7.7 months (95% confidence interval, 7.1-8.3). Median OS of patients with epithelioid MM was significantly longer than that of patients with biphasic (p = 0.030) or sarcomatoid (p < 0.001) MM. Surgical resection was performed in 172 patients (18.5%) and 449 (48.3%) received systemic chemotherapy. Survival of patients treated with both surgery and systemic chemotherapy was favorable. Median OS of patients in the late phase of the study period (2006-2008) was significantly longer than that in the early phase (2003-2005) (8.1 vs. 7.5 months, p = 0.008). Independent favorable prognostic factors included age younger than 70 years, female gender, epithelioid subtype, and clinical stage I-III. Multivariate analysis demonstrated that patients who had radical surgery and systemic chemotherapy showed a longer survival, though this could be due to selection bias of patients.