Prognostic effect of red cell distribution width-to-platelet ratio in colorectal cancer according to tumor stage and localization

Introduction: Colorectal cancer (CRC) is one of the most common cancers worldwide and survival is still approximately 24 months. Recently, importance of the molecular features, tumor localization, and also inflammatory status is increased, and most of these entities can be used as a predictive marker for colon tumor. However, since most of these tests are expensive and unachievable, there is a need for new prognostic and predictive markers that can be used easily and are inexpensive. Aim: We aimed to investigate the prognostic effect of red cell distribution width (RDW)-to-platelet ratio (RPR) which reflects inflammatory status and can be calculated basically by using center blood count (CBC) parameters on CRC according to tumor stage and localization. Methods: Newly diagnosed 312 CRC patients between 2010 and 2016 were retrospectively analyzed. Patients' demographics, including survival data and tumor characteristics, were obtained from medical charts. RPR was calculated using CBC parameters at the time of diagnosis. Cutoff value for RPR was set at 0.05 and the patient population was divided into two arms (arm A: RPR >= 0.05 and arm B: RPR < 0.05). The patients were stratified according to the tumor stage (early and advanced disease) and tumor localization (right sided and left sided). Results: Totally, 312 patients were enrolled to the study. Nearly 81.9% of the patients were at early stage and 18.1% were at advanced stage at the time of diagnosis. In patients with early-stage disease, no significant disease-free survival and overall survival (OS) was found in both arms (P = 0.88 and P = 0.085, respectively). In arm A, OS was nonsignificantly better in the entire and left-sided advanced tumor compared to arm B. In patients with right-sided advanced cancer, OS was statistically significantly better for arm A compared to arm B (median OS; RPR >= 0.05: 24.8 months vs. < 0.05: 13.9 months; P = 0.035). Discussion: RPR can be a useful prognostic marker in CRC, especially in right-sided advanced tumors. Conclusion: RPR can be used as a prognostic marker in CRC but should be validated with further investigation.