Diffuse Malignant Pleural Mesothelioma: a Multi-institutional Clinicopathological Study

Purpose: The relative rarity of malignant pleural mesothelioma (MPM) in Japan makes it difficult to perform a large-scale clinicopathological study of this tumor at a single institute. Thus, we performed a multiinstitutional study to evaluate the current status of diagnosis and treatment in Japan.

Methods: We analyzed the records of 65 patients with MPM, obtained from the 13 institutions comprising the Japanese Chiba Multicenter Study Group.

Results: In 56 patients, the tumor was detected after a visit to a medical facility for subjective symptoms such as chest pain, shortness of breath, and cough. It took a median period of 2 months from the initial visit to establish the diagnosis. The overall survival rates of 33 patients with unresectable MPM 1, 2, and 3 years after the diagnosis were 40.5%, 10.8%, and 0%, respectively, whereas those of 32 patients who underwent surgery were 67.9%, 35.0% and 10.9%, respectively (P=0.0035). According to multivariate analysis, histological type, International Mesothelioma Interest Group clinical stage, sex, and the presenting symptom of shortness of breath were significant prognostic factors.

Conclusions: The definitive diagnosis of early MPM is difficult, but establishing the best diagnostic modality would improve survival rates, since radical surgery is likely to be effective for resectable disease.