Prognostic Value of Red Cell Distribution Width (RDW) In Colorectal Cancer. Results from a Single-Centre Cohort on 591 Patients

Aim: RDW has been extensively used to discriminate the types of anaemia, as it reflects the degree of heterogeneity of erythrocyte volume (anisocytosis). Recent studies suggested its role as an inflammatory marker, and an increased RDW has been regarded as a risk factor for mortality in a variety of acute and chronic conditions. Increasing evidence advocates the prognostic role of RDW in various tumours, including breast and ovarian cancer. The aim of this study was to investigate its role as a prognostic factor for overall (OS) and cancer-related survival (CRS) in patients who underwent surgery for colorectal cancer (CRC). Material and methods: From January 2005 to December 2016, 1347 patients underwent surgery for CRC at the Division of General and Hepatobiliary Surgery, University of Verona Hospital Trust. Patients with evidence of infection or inflammatory conditions, and those who underwent emergency surgery were excluded; the minimum follow-up time was 24 months. The data were retrieved from a retrospective database. The optimal cut-off value for RDW was set at 14.1%; accordingly, two groups were considered: those with a value equal or lower than 14.1% (L-RDW), and those with a value higher than 14.1% (H-RDW). Results: A total of 591 patients met the inclusion criteria. The preoperative mean RDW value (±SD) was 15.2 (±3.2); 283 patients (47.9%) were classified as H-RDW. RDW was higher in patients with age above the median (p<0.001) and in colonic tumours (p<0.001). The mean value of RDW rose from pT1 to pT4 tumours (p=0.012). H-RDW correlated with age above the mean (p<0.001), colonic location of the lesion (p=0.012), pT (p=0.034) and TNM stage (p=0.049). Finally, H-RDW was significantly associated with the intent of surgery (p<0.001): almost 50% of patients who underwent a non-curative resection presented H-RDW, compared to 19.3% in R0 resections. OS was significantly lower in patients with H-RDW (p=0.043). Interestingly, OS was similar between groups up to 5 years after surgery (L-RDW 74.7% vs H-RDW 72.3%), whereas the difference increased on a longer follow-up (OS at 10 years 54% H-RDW vs 68.1% L-RDW). CRS was similar in the two groups (p=0.775). Survival rates were also examined stratifying patients according to TNM stage: worse OS was associated with H-RDW only in early stages (Stage 0-I; p=0.001), whereas there was no difference for stages II-IV. Multivariate analysis confirmed that H-RDW was not an independent prognostic factor. Conclusions: Although H-RDW correlated with some negative clinical-pathological factors, it did not seem to independently influence OS and CRS.