Changing patterns of lung cancer; (3/4 in.) 1.9 cm; still a safe length for bronchial resection margin?

Surgical resection is the best treatment modality in non-small cell lung cancer (NSCLC). As a guideline, it is suggested that at least a bronchial resection margin of 1.9 cm from the macroscopic tumor might provide a tumor-free margin in lung cancer. In some recent reports, there is great emphasis on the changing histopathological patterns of lung cancer, but no concern for the proximal extension of lung cancer. The aim of this study was to determine the validity of this guideline in the current time.

Surgically resected specimens of NSCLC cases (n = 70) were examined. The bronchial tree including tumor was dissected and beginning from the edge of the visible tumor, the bronchus were cut into serials in its transverse plane, 5 mm apart from each other. Cut sections were examined for proximal extension of tumor at different levels.

Microscopic proximal extension was observed in 24.2% (n = 17/70) of all the cases. Peribronchial extension (n = 9/17) (52.9%) was more predominant compared with bronchial extension (n = 8/17) (47.0%). Squamous cell carcinoma (n = 11/38) (28.9%) showed proximal extension more than adenocarcinoma (n = 5/23) (21.7%). Adenocarcinoma showed more peribronchial extension (n = 4/5) (80.0%) whereas squamous cell carcinoma (n = 7/11) (63.6%) showed more bronchial extension. The farthest extension was 3.0 cm for adenocarcinoma and 2.0 cm for squamous cell carcinoma. Excluding tumor positive specimens beyond 1.5 cm level to the bronchial resection margin, all tumors accounted for 96% of the whole series.

Microscopic proximal extension of lung cancer occurs in 24.2% of NSCLC cases. Squamous cell carcinoma extends more proximally compared with adenocarcinoma in ratio whereas adenocarcinoma extends more in length. A bronchial resection of 1.5 cm in length from the macroscopic tumor will provide clear margins in 93% of NSCLC cases.