A prognostic parameter in advanced non-small cell lung cancer: the ratio of hemoglobin-to-red cell distribution width Abstract Background This study aims to investigate the prognostic value of the ratio of hemoglobin–RDW (HRR) at diagnosis, in terms of overall survival (OS) and progression-free survival in patients with advanced non-small cell lung cancer (NSCLC). Methods Patients with metastatic NCCLC who attended two separate medical oncology clinics between April 2013 and December 2017 were retrospectively screened. HRR was calculated as Hgb (g/dL) divided by the RDW (%). Patients were assigned to either the low HRR group or high HRR group. Results A total of 153 patients were included in the study. The cuff-value for HRR was taken as 0.88. Among the low and high HRR groups, Glasgow prognostic scores (GPS), neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR) and weight loss were statistically significantly different (p < 0.05). OS was found to be 5.6 months in the low HRR group and 13.9 months in the high HRR group (p < 0.001) while PFS was 5.1 months and 8.6 months in these two groups, respectively (p < 0.001). Univariate and multivariate analyses revealed that low HRR was an independent factor, predictive of both OS (p = 0.03, Hazard Ratio (HR) = 1.607, 95% CI = 1.041–2.480) and PFS (p < 0.001, HR = 2.635, 95% CI = 1.667–4.166) in advanced NSCLC. Conclusion This is the first study to show that low HRR is associated with poor OS and PFS in patients with advanced NSCLC. Thus, hemoglobin and RDW which can be easily measured in routine practice may be used as a prognostic tool in these patients.