Clinicopathologic study of mucoepidermoid carcinoma of the lung.

Abstract Mucoepidermoid carcinoma is a relatively uncommon form of lung cancer and has generally been viewed as a low grade malignant tumor. The present study was undertaken to establish a clinicopathological characterization of patients with this cancer who were treated surgically at Kanazawa University Hospital. Between 1973 and 1975, 10 patients with mucoepidermoid carcinoma were surgically treated in our department. The 10-year survival rate after surgery for the central type of carcinoma was 67%, while the 4-year survival rate for the peripheral type was 25%. When the survival rates were analyzed in terms of Conlan's grades, grade 1 cases had a 10-year survival rate of 80%, while the 4-year survival rate for grade 2 and 3 cases was 20%. The four patients who survived 5 years or more following surgery all had a grade 1 central type tumor. These results suggest that mucoepidermoid carcinoma of the lung should not be viewed uniformly as a low grade malignant tumor, but that this tumor can sometimes be highly malignant with a poor prognosis. Since this tumor is often difficult to distinguish from adenosquamous carcinoma, and because accurate distinction between these two types of tumor seems to be essential for establishing a prognosis, there is an urgent need for a valid pathological method for differential diagnosis of mucoepidermoid carcinoma.