Clinical evaluation of stereotactic radiation therapy for recurrent or second primary mediastinal lymph node metastases originating from non-small cell lung cancer

Aims: To evaluate the safety and efficacy of stereotactic radiotherapy (SRT, both stereotactic body RT [ SBRT] and fractionated stereotactic RT [ FSRT]) in the treatment of patients with recurrent or second primary mediastinal lymph node metastases (R/SP-MLNMs) originating from non-small cell lung cancer (NSCLC). Methods: Between 10/2006 and 7/2013, patients with R/SP-MLNMs originating from NSCLC were enrolled and treated with SRT at our hospital; their data was stored in prospectively-collected database. The enrolled patients were divided into Group A (without prior RT) and Group B (with prior RT). The primary end-point was overall survival (OS). The secondary end-points were the MLNM local control (LC), the time to symptom alleviation, and toxicity using the Common Terminology Criteria for Adverse Events (CTCAE v4.0). Results: Thirty-three patients were treated (16 in Group A with 19 R/SP-MLNMs and 17 in Group B with 17 R/SP-MLNMs). For the entire cohort, the median OS was 25.5 months with a median follow-up of 20.9 months (range, 3.2-82). The 1-year and 3-year actuarial LC rates were 100% and 86%, respectively. Symptom alleviation was observed in 52% of patients, after a median of 6 days (range, 3-18). CTCAE v4.0 >= Grade 3 toxicities occurred in 5 patients (15%; all in Group B); among them, Grade 5 in 2 patients. Conclusions: We recommend exercising extreme caution in using SRT for R/SP-MLNMs in patients who received prior RT (particularly to LN station 7). For patients without previous RT, SRT appears to be safe and efficacious treatment modality; prospective studies are warranted.