Radiosurgery and fractionated stereotactic radiotherapy in oligometastatic/oligoprogressive non-small cell lung cancer patients: Results of a multi-institutional series of 198 patients treated with "curative" intent.

OBJECTIVES: stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT) are a therapeutic option for Oligometastatic/Oligoprogressive (OM/OP) NSCLC. This retrospective multicentre analysis aims to analyse clinical outcomes and treatment related toxicity of patients treated to all sites of know disease with SRS and/or FSRT for OM/OP NSCLC in 8 Italian radiation oncology centres. MATERIALS AND METHODS: From January 2016 to January 2017 198 OM/OP NSCLC patients (pts) were treated in 8 Centres. Inclusion criteria were as follows: 1-5 lesions at onset or after previous systemic treatment; Pts must have all metastatic lesions treated. Endpoints analysed were local progression free survival (LPFS); out-of-field recurrence free survival (OFPS); progression free survival (PFS); overall survival (OS). Time to New systemic Therapy free survival (TNT) and toxicity were also analysed. RESULTS: At the time of radiotherapy, 119 pts (60 %) were treated for a single lesion, 49 (25 %) for 2 lesions, 30 (15 %) for 3-5 metastases. Total number of lesions treated was 333: 204 brain, 68 lung, 24 bone, 16 nodal, 12 adrenal, 8 liver and 1 soft tissue. 83/198 pts (41.8 %) had the primary tumour controlled at the time of the SRT. After a median follow-up of 18 months, median OS and PFS were 29.6 months and 10.6 months, respectively. One year LPFS and OPFS were 90 % and 47 %, respectively. Median TNT was 10 months. At univariate analysis factors associated with better OS were PS 0-1; controlled primary tumour, 1-2 lesions; extracranial metastasis. Multivariate analysis confirmed number of lesions <3 and extracranial metastasis to be related with better survival (Relative Risk 0.4 and 0.41, respectively). Two cases of death possibly related to brain radionecrosis were observed. CONCLUSION: OM/OP NSCLC pts treated with an ablative SRT to all metastatic sites have fair outcomes with acceptable toxicity. Better results might be achieved in case of low disease burden and extracranial possibly when primary tumour is controlled.