Addition of radiotherapy to the primary tumour in oligometastatic NSCLC: A systematic review and meta-analysis

Abstract

Oligometastatic non-small cell lung cancer (NSCLC) has a discrete number of distant lesions (<5) that can be amenable to radical treatment. The treatment of the primary lung tumour in such stage IV cases is still debated. We conducted a systematic review and meta-analysis to evaluate the outcome of these patients and the added benefit in terms of overall survival (OS) and progression-free survival (PFS) when radical treatment of the primary tumour with radiotherapy (RT) was delivered. PubMed, EMBASE and Cochrane Library were systematically searched to identify relevant studies published up to July 2018. Prospective trials and retrospective series comparing RT vs no RT to the primary NSCLC in the presence of oligometastases were included. Hazard ratios (HRs) for OS and PFS were aggregated according to a fixed or random effect model. Twenty-one studies for a total of 924 synchronous oligometastatic NSCLC were analysed. Median OS and PFS were 20.4 and 12 months. Pooled 1-2-3 and 5-year OS were 70.3%, 43.5%, 29.3% and 20.2% respectively. Overall survival was improved with the addition of thoracic RT (HR = 0.44, 95%CI 0.32-0.6; P < 0.001). Similarly, RT added to the primary tumour increased PFS (HR = 0.42, 95%CI 0.33-0.55; P < 0.001). The only variable associated with the median OS was the year of publication with most recent series associated with a better outcome. In patients with oligometastatic NSCLC and disease controlled with ablative therapy of distant metastases, a consolidation with radical RT to the primary tumour is associated with better survival and could be considered as a treatment modality in selected cases.

Keywords: Meta-analysis; Non-small cell lung cancer; Oligometastases; Primary tumour; Radiotherapy.