Unpredictable course of small cell undifferentiated lung carcinoma.

Twenty-nine patients with small cell lung carcinoma were examined as to ultrastructural morphology, stage of disease, and survival. Although all tumors met the light microscopic criteria for oat cell carcinoma, only 19 (66%) contained neurosecretory granules characteristic of this tumor. Of 12 patients undergoing pulmonary resection, five of six patients with non-neurosecretory tumors and two of six patients with neurosecretory (true oat cell) tumors survived more than 2 years. Survival of all patients with Stage I or II disease was significantly different from that of patients with Stage III disease. Stage together with ultrastructural morphology may carry important therapeutic and prognostic implications. Pulmonary resection appears to be effective treatment for certain subsets of patients with small cell undifferentiated carcinoma.