Histological changes after radiation therapy in patients with lung cancer: a prospective study.

BACKGROUND

Radiotherapy for lung cancer may induce pneumonitis. However, histological effects of radiotherapy on normal lung tissue are unknown. Transbronchial biopsy (TBB) is safe and accurate in monitoring parenchymal lesions in lung-transplanted patients. The aim of this prospective study was to evaluate whether histological changes of the healthy lung parenchyma after radiotherapy are present on TBB biopsies.

PATIENTS AND METHODS

Twelve patients with lung cancer necessitating radiation therapy participated in the study. Serial TBBs were obtained from lung parenchyma contra-lateral to the tumor before, just after radiotherapy, and at six months post-irradiation. Evaluation of each specimen was based on the presence of congestion, inflammation, hemorrhage and fibrosis.

RESULTS

A significant increase of interstitial fibrosis (thickness) and congestion was observed between the point prior to radiotherapy and after completion of radiotherapy (p=0.047), as well as between the pre-radiotherapy point and at six months after radiotherapy (p=0.014). Six patients (50%) showed intra-alveolar fibroblastic growth after radiotherapy. No patient showed clinical or radiographic findings of radiation pneumonitis.

CONCLUSION

Even in the absence of clinical or radiographic findings, the lung parenchyma contra-lateral to the tumor suffers early histological lesions after radiation therapy, as monitored by serial TBBs.