Purpose/Objective(s): In 2011, we reported the clinical outcome of radiotherapy for hilar and/or mediastinal lymph node (LN) metastases developing after stereotactic body radiotherapy (SBRT) for stage I nonsmall cell lung cancer (NSCLC), in comparison with that for postoperative LN metastases. The aim of this study is to evaluate 5-year results for these patients. Materials/Methods: Between 2004 and 2014, 27 patients with hilar and/or mediastinal LN metastases without local recurrence and distant metastasis after SBRT (n Z 14) or surgery (n Z 13) were treated with definitive conventional radiotherapy. The median follow-up period was 11 months (range, 4-92) in the post-SBRT group and 25 months (range, 5-126) in the post-surgery group. Twelve of the 14 patients (86%) in the post-SBRT group were judged medically inoperable at the time of SBRT. Prior to radiotherapy for LN metastases, absence of local recurrence and distant metastases was confirmed by FDG-PET and/or other imaging modalities in both groups of patients. Both groups were treated conventionally with 2-Gy daily fractions using 10-MV photons. The median total dose for treating metastatic lymph nodes was 60 Gy (range, 54-66) for the post-SBRT group and 66 Gy (range, 60-66) for the post-surgery group. Only 1 of the 14 post-SBRT patients and 9 of the 12 post-surgery patients received chemotherapy. Survival and local control rates were calculated by Kaplan-Meier method, and differences between the curves were examined by logrank test. Toxicities were evaluated with the Common Terminology Criteria for Adverse Events version 4.0. Results: Overall survival, cause-specific survival, progression-free survival, and local control rates at 3 years after mediastinal irradiation were 21%, 45%, 21%, and 64%, respectively, for the 14 patients in the post-SBRT group. These rates were 54%, 54%, 39%, and 92%, respectively for the post-surgery group (P Z .066, .64, .38, and .71, respectively). Four in the post-SBRT group lived 3 or more years (range, 36-92 months) after mediastinal irradiation. A grade 5 pulmonary toxicity was observed in 1 of the post-SBRT patients. The other toxicities were all grade 2. There was no significant difference in the incidence of ! grade 2 pulmonary toxicity (43% for the post-SBRT group vs 31% for the post-surgery group, PZ .80; chi-square test). Conclusion: A proportion of patients achieved long-term survival by conventional radiotherapy. The probability of long-term survival did not seem to differ significantly from that in postoperative recurrent cases. Radiotherapy in this setting appears reasonably well tolerated.
