AbstractA retrospective study was conducted of 993 malignant tumors of the lung in 977 patients. The male‐female sex ratio was 2.6:1. The age distribution of the males did not differ from that of the females and the overall mean age was 64.3 ± 9.5 years (range, 13–85 years). Forty‐three percent of the patients were in their seventh decade. The location was peripheral in 81% of the tumors and central in 19%. Of the central tumors, 85% were squamous cell (epidermoid) carcinoma (SCC), while 58% of the peripheral tumors were adenocarcinoma (ADENO). In males, 49% of all tumors were SCC and 36% ADENO, while in females 76% were ADENO. The incidence of positive lymph node metastasis increased in parallel with the pT status in both central and peripheral carcinomas. However, it was noted that, of peripheral lung carcinomas, no SCC with a diameter of 15 mm or less had lymph node metastasis, whereas 18.9% of the ADENO of this size were positive for lymph node metastasis. These results indicate that lymph node metastasis can occur even in small‐sized peripheral ADENO less than 15 mm. Thus, early detection and surgery together with mediastinal lymph node dissection are necessary even for small‐sized tumors to improve the prognosis in patients with peripheral ADENO of the lung. © 1995 Wile