Stage III Lymph Node–Positive Non‐Small‐Cell Lung Cancer Patients With or Without Lymph Node Irradiation by Stereotactic Body Radiation Therapy: Propensity Score–Matched Analysis

PURPOSE: This study compared the local control (LC) and survival of patients with stage III lymph node-positive non-small-cell lung cancer (NSCLC) who received lymph node irradiation (LNs R+) and those who did not (LNs R-). METHODS: We retrospectively reviewed patients with stage III LN-positive NSCLC who underwent stereotactic body radiotherapy (SBRT) with or without lymph node irradiation between January 2013 and December 2018. Using propensity score matching (PSM) analyses, we compared the rates of LC, progression-free survival (PFS), overall survival (OS), and acute/late toxicities between the two groups. RESULTS: We retrospectively analyzed 201 patients, of whom 52 received LN irradiation and 149 did not. The median LC and OS were 59.7 months (95% CI: 51.1-62.9 months) and 36.3 months (95% CI: 32.6-40.0 months), respectively. After the PSM analysis, 52 patients were included in each group. The median LC (30.6 months and not reached, HR 1.296, 95% CI: 0.733-2.294, p = 0.371) and OS (30.3 months and 31.6 months, HR 0.969, 95% CI: 0.628-1.496, p = 0.887) were similar between the LN R+ group and the LN R- group. Total tumor size, tumor location, and biologic equivalent dose (BED) were independently associated with LC (p < 0.05). The incidences of acute radiation esophagitis (p = 0.006) and late pulmonary interstitial fibrosis (p = 0.046) were significantly higher in the LN R+ group than in the LN R- group. CONCLUSIONS: SBRT is safe and effective in stage III LN-positive NSCLC patients. Omitting elective nodal irradiation achieves comparable survival to irradiating involved lymph nodes while significantly reducing toxicity. These findings support the development of novel combination strategies.