Proximal bronchial extension with special reference to tumor localization in non-small cell lung cancer

Surgery is the optimal treatment in patients with non-small cell lung cancer (NSCLC) and tumor-negative bronchial resection margins should be maintained for a curative resection. The epidemiology of NSCLC, including the aspects of tumor localization, has been changing during the recent decades. The aim of this study was to evaluate microscopic proximal bronchial extension with special reference to the site of the tumor.

Surgical specimens of 70 NSCLC cases were examined histologically for proximal bronchial extension of the tumor. The entire bronchial tree with the tumor was extracted from the specimen and serially cut at a thickness of 5 mm in the transverse plane of the bronchus. Microscopic proximal extension of the tumor was classified as either endobronchial or peribronchial.

Thirty-three (47.1%) tumors had central and 37 (52.9%) had peripheral localization. Among the central and peripheral tumors, 10 (30.3%) and seven (18.9%) had microscopic proximal extension, respectively. In total, the mean length of proximal extension was 10.94 +/- 7.07 mm. The mean length of extension for peripheral tumors was 15.71 +/- 8.38 mm, significantly greater than that of central tumors, which was 7.60 +/- 3.47 mm (P = 0.026). Peripheral tumors showed a significant peribronchial extension (P = 0.024).

A greater percentage of central tumors show microscopic proximal bronchial extension, whereas the length of microscopic proximal bronchial extension is significantly greater in peripheral tumors. Peripheral tumors preferentially have a peribronchial extension pattern.