Stereotactic body radiotherapy for primary non-small cell lung cancer patients with clinical T3-4N0M0 (UICC 8th edition): outcomes and patterns of failure

The evidence for stereotactic body radiotherapy (SBRT) is meagre for patients with clinical T3-4N0M0 non-small cellung cancer (8th Edition of the Union for International Cancer Control (UICC)). This study retrospectively investigated clinical outcomes following SBRT for such patients. Among consecutive patients treated with SBRT, patients staged as cT3-4N0M0 by all criteria were examined, most of whom were unsuitable to chemoradiotherapy due to their fragile characters. Clinical outcomes were evaluated and factors associated with outcomes were investigated. Between 2005 and 2017, 70 eligible patients (T3: 58, T4: 12; median age 81 (63-93) years) were identified. Median follow-up duration was 28.6 (1.0-142.5) months. No adjuvant chemotherapy was administered. The 3-year local recurrence rates were 15.8% and 16.7% in T3 and T4 patients, respectively, and they were significantly lower in the high-dose group (3.1% vs 28.6%, P<0.01). Multivariate analyses showed that the dose-volumetric factor was the significant factor for local recurrence. The 3-year regional and distant metastasis rates, cancer-specific mortality, and overall survival in T3 and T4 patients were 22.7% and 25.0%, 26.5% and 33.3%, 32.2% and 41.7%, and 39.5% and 41.7%, respectively. Only age was correlated with overall survival. Radiation pneumonitis >= grade 3 and fatal hemoptysis occurred in 3 and 1 patients, respectively. SBRT for cT3-4N0M0 lung cancer patients achieved good local control. Survival was rather good considering that patients were usually frail, staged with clinical staging, and were not given adjuvant chemotherapy, and it may be comparable to surgery. To validate these outcomes following SBRT, a prospective study is warranted.