Sometimes microscopic residual tumor is found at the bronchial resection margin despite an apparently complete resection of lung cancer. This may adversely affect the patient's prognosis. Its impact on survival is unclear.

The records of 834 patients with resected stage I non-small cell lung cancer were studied. Patients with complete resection were assigned to the complete resection group (n = 802); patients with microscopic residual tumor at the bronchial resection margin that was accepted were assigned to the residual tumor group (n = 23). Residual tumor was classified as carcinoma in situ, mucosal residual disease, or peribronchial residual disease.

The 5-year survival in the patients in the complete resection group was 54%; it was 58% in the residual tumor group with carcinoma in situ and 27.3% in the residual tumor group with invasive tumor (mucosal residual disease or peribronchial residual disease). The difference in survival between patients in the complete resection group and patients in the residual tumor group with invasive tumor was significant (p = 0.03).

The presence of mucosal or peribronchial residual disease, but not carcinoma in situ, at the bronchial resection margin in patients with stage I non-small cell lung cancer has an adverse effect on survival.