Postoperative Radiotherapy for Incompletely Resected Non-small Cell Lung Cancer: Clinical Outcomes and Prognostic Value of the Histological Subtype

Postoperative radiotherapy/Non-small cell lung cancer/Squamous cell carcinoma/Histological subtype/Adenocarcinoma. The purpose of this study was to evaluate the efficacy and toxicity of the postoperative radiotherapy in patients with incompletely resected NSCLC, and to investigate whether the histological subtype is a prognostic factor. Forty-one incompletely resected NSCLC patients who underwent postoperative radiotherapy were retrospectively analyzed. The microscopi c residual tumor (R1 group) was recognized in 23 patients, and the macroscopic residual tumor (R2 group) in 18. The postoperative pathological stages were I (n = 3), II (n = 8), IIIA (n = 17), and IIIB (n = 13). The histology included squamous cell carcinoma (n = 2 3), adenocarcinoma (n = 14) or other types (n = 4). The first site of disease progression was distant metastases alone for 3 (13%) of 23 with squamous cell carcinoma, and for 9 (64%) of 14 with adenocarcinoma (p < 0 .01). The 5-year overall, local control, disease-free, and distant metastasis-free survival rates were 56%, 63%, 37% and 49%. Univariate analyses showed that squamous cell carcinoma histology, N01 stage and the R1 group were significant predictors for better disease-free and distant metastasis-free survival. Multivariate showed that squamous cell carcino ma and N0-1 stage were significant predictors for better distant metastasis-free survival. Toxicity was generally mild; Grade 3 toxicities occurred in 3 patients (neutropenia, radiation pneumonia and esophageal stenosis), and no acute and late toxicities of G rade 4 to 5 were observed. In conclusion, postoperative radiotherapy for incompletely resected NSCLC could achieve a relatively high local control rate without severe toxicity. However, different treatment strategies for non-squamous cell carcinoma should be considered, because of the higher risk for the distant metastases.