Use of the neutrophil to lymphocyte ratio (NLR) and the platelet to lymphocyte ratio (PLR) for prognostication of patients with early-stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiation therapy (SBRT): a systematic review

Background and purposeThe neutrophil to lymphocyte (NLR) and platelet to lymphocyte (PLR) ratios are markers of systemic inflammation with uncertain prognostic utility. Thus, we conducted a systematic review of NLR and PLR as prognostic factors for overall survival (OS), progression-free survival (PFS), and local control (LC) of patients with stage 1 non-small cell lung cancer (NSCLC) following stereotactic body radiotherapy (SBRT) with curative intent.Methods and materialsThe EMBASE, Cochrane Library, MEDLINE, and PubMed databases were searched from January 1996 until September 2017 for primary research studies and systematic literature reviews that reported pre-treatment NLR and PLR of patients with stage 1 NSCLC and OS, PFS, and/or LC of patients following SBRT.ResultsAn electronic database search identified 292 articles, of which five were eligible for inclusion. Cutoffs for a high NLR ranged from 2.18 to 3.155 while cutoffs for a high PLR ranged from 146 to 187.27. Four studies reported outcomes related to disease control and had mixed results as to the utility of the NLR and PLR as a prognostic factor. Four studies analyzed the association between high NLR cutoff with OS and all found a statistically significant association. Three studies examined a high PLR cutoff and all found a statistically significant association with worse OS.ConclusionNLR and PLR appear to be relevant prognostic factors for OS following lung SBRT in stage I NSCLC. They may serve as accessible and inexpensive tests to aid in clinical decision-making but prospective validation is necessary.