Correlation of tumor size and lymph node metastasis with the efficacy of postoperative radiotherapy in non-small cell lung cancer

Abstract

Objective To analyze the factors affecting the efficacy of postoperative radiotherapy (PORT) in node-positive non-small cell lung cancer (NSCLC). Methods 480 patients with stage N_1-N_2 NSCLC after radical surgery were retrospectively reviewed. Of them, 267 patients received adjuvant chemotherapy and 121 received PORT. All patients were grouped based on the N stage, tumor size and lymph node positive ratio (the percentage of positive lymph nodes from the detected lymph nodes, LNPR). Group 1 included patients with tumor size ≤3 cm and LNPR ≤33%, group 2 was tumor size > 3 cm or LNPR > 33%, and group 3 was tumor size > 3 cm and LNPR > 33%. The endpoints were the local recurrence free survival (LRFS) and overall survival (OS). Kaplan-Meier method and Cox's proportional hazards regression model were used for the statistic analyses. Results PORT improved the overall survival only in patients with N_2 disease. Both tumor size and LNPR significantly influenced the efficacy of PORT. The 5-year LRFS for patients with vs. without PORT in the group 1, 2 and 3 were 55% vs. 60% (χ~2 = 0.03,P-0.869), 42% vs. 50% (χ~2 =0.31,P=0.547),and 62% vs. 52% (χ~2=4.25,P=0.036), respectively;and the corresponding OS were 22% vs. 50% (χ~2 = 1.65 ,P =0. 199), 26% vs. 22% (χ~2= 0. 13,P=0.786) and 42% vs. 16% (χ~2= 15.33,P=0.000), respectively. Conclusions Tumor size and LNPR significantly impact the efficacy of PORT . For patients with stage N_2 NSCLC , PORT could improve local recurrence free survival and overall survival when tumor size > 3 cm and LNPR >33%. Key words: Neoplasms, non-small cell lung/surgery; Neoplasms, non-small cell lung/ radiotherapy; Prognosis