Low-grade malignant tumors of the lung: is lymph node dissection necessary?

Low-grade malignant tumors (LGMT) of the lung were surgically treated in our institute between 1981 and 1997. Both the characteristics and prognosis were examined. We studied 10 cases with LGMT of the lung, male to female ratio 1:1, age range 15 to 71 years, mean 55 years, 6 central and 4 peripheral. Five patients had lobectomy, 3 had sleeve lobectomy and 2 had bilobectomy. Pathologically, 5 samples were typical carcinoid, 3 were mucoepidermoid carcinoma and 2 were adenoid cystic carcinoma. None of the patients had lymph node metastasis. Nine patients were stage I and one stage IIIA. Seven patients underwent absolutely curative resection; 2, relatively non-curative resection; 1, non-curative resection. In preoperative examination, only 4 patients was diagnosed correctly and the others were misdiagnosed. Mean survival time was 167.5 months. One patient died from causes other than the primary cancer and the others are surviving (range 2-173 months). The LGMT group was significantly younger and had a significantly better prognosis compared with the control group (p=0.02). Mediastinal lymph node dissection is suggested to be omitted. However, further accumulation of cases is necessary regarding to the omission of lymph node dissection.