Prognostic implications of microscopic proximal bronchial extension in non-small cell lung cancer

The loss of approximately one third of early stage lung cancer patients undergoing complete resection by the end of 5 years implies the existence of unknown or undetected factors at the time of operation. We investigated the possible correlation between microscopic proximal bronchial extension (MPBE) and survival with clinicopathologic features in patients with non-small cell lung cancer.

The bronchial tree with the tumor was dissected and extracted from the lung parenchyma in a total of 62 surgical specimens with non-small cell lung cancer. The tumor-related bronchus was sectioned into serial blocks at a thickness of 5 mm in the transverse plane. Histologically, cut serial sections were examined for MPBE.

A total of 15 (24.2%) specimens showed MPBE, whereas 47 (75.8%) specimens showed no evidence of MPBE. The median survival time of MPBE-positive patients was 10.0 months, whereas that of MPBE-negative patients was 42.0 months. The 5-year survival rates of MPBE-positive and MPBE-negative groups were 13.3% and 35.8%, respectively, which was a significant difference (p = 0.0203). Multivariate analysis revealed lymph node status (p = 0.0161), histology (p = 0.0268), and MPBE-positivity (p = 0.0447) as independent prognostic factors.

Microscopic proximal bronchial extension has an adverse effect on survival in non-small cell lung cancer.