Prognostic Factors of Survival after Radiotherapy for Lung Cancer–The Impact of Smoking Pack Years

Background/Aim: The prognostic role of smoking pack years after thoracic irradiation for lung cancer needs further clarification, since previous studies showed conflicting results. Therefore, this study investigated potential prognostic factors for survival including pack years in 170 lung cancer patients receiving local radiotherapy. Patients and Methods: Twelve factors were retrospectively evaluated for survival including age, sex, tumor site, histology, primary tumor stage, nodal stage, distant metastasis, radiation dose, upfront surgery or systemic treatment, pulmonary function, and number of pack years. Results: On univariate analyses, absence of distant metastasis (p=0.049), radiation dose >56 Gy (p=0.019), and ≤40 pack years (p=0.005) were significantly associated with better survival. In the multivariate analysis, number of pack years (hazard ratio 2.18, 95% confidence interval 1.25-3.82, p=0.006) maintained significance; distant metastasis (p=0.34) and radiation dose (p=0.16) were not significant. Conclusion: Number of pack years was an independent predictor of survival after thoracic irradiation for lung cancer.