ESTRO 2021 Abstract Book

S1038

ESTRO 2021

Conclusion High preoperative WBC, peripheral platelet, ANC, NLR and SII were poor prognostic markers for OS in rectal cancer patients receiving long-course preoperative CRT followed by radical operation. Patients with high preoperative Hb levels might have better prognosis than those with low levels in rectal cancer after long- course preoperative CRT. Compared with ANC and NLR, SII might be more powerful for predicting survival outcome in patients with rectal cancer after long-course preoperative CRT. PO-1260 Neutrophil and platelet-to-lymphocyte ratio as prognostic factors in locally advanced rectal cancer V. Duque Santana 1 , F. Lopez-Campos 1 , M. Martin-Martin 1 , A. Hernandez Corrales 1 , L. Pelari Mici 2 , M. Valero Perena 1 , S. Sancho Garcia 1 1 Ramon y Cajal University Hospital, Radiation Oncology, Madrid, Spain; 2 Ramon y Cajal University Hospital , Radiation Oncology, Madrid, Spain The standard therapy for locally advanced rectal cancer is based on neoadjuvant chemoradiotherapy (nCRT) with fluoropyrimidines. There are different biomarkers used as prognostic factors in these tumors. Some studies indicate the use of the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) as prognostic factors in this clinical scenario. PURPOSE The aim of the study is to evaluate NLR and PLR as prognostic factors of progression-free survival (PFS) and overall survival (OS) and as predictive factors of pathological complete response (pCR) using Ryan tumor regression scoring system on surgical specimens, in patients with locally advanced rectal adenocarcinoma who received nCRT and radical surgery. Materials and Methods We retrospectively evaluated patients with locally advanced rectal adenocarcinoma (T3-T4, N1-N3, M0 according to the TNM classification, AJCC 8 th edition) who received neoadjuvant chemoradiotherapy based on fluoropyrimidines and radical surgery. Complete blood cell count before nCRT were obtained to calculate NLR and PLR. We made subgroups of patients according to NLR and PLR. We obtained the cut-off point of these ratios based on receiver operating characteristic analysis. We analyzed OS and PFS using the Kaplan-Meier method and Cox proportional hazard models. The relationships between NLR/PLR and pCR, along with other clinical-pathological characteristics were evaluated by Pearson´s χ2 or Fisher´s exact test as appropriate. Univariate and multivariate analyses were performed using a logistic regression model. Results Between February 2012 and February 2017, 100 consecutive patients were treated according to the reported schedules. Median age was 76 years (68-83). All patients received radiotherapy up to 50,4 Gy and 5-FU-based chemotherapy. 97% completed nCRT and 100% completed neoadjuvant radiotherapy. 38% had elevated basal NLR (cut-off >1,95), 50% had elevated basal PLR (cut-off >133). After a median follow-up of 72 months (55- 88), a lower PFS was obtained in the high NLR subgroup (Long Rank, Mantel-Cox 5,165, p=0,023) and in the high PLR subgroup (Long Rank, Mantel-Cox 13,971, p=0,001). Multivariate analysis showed that PLR (p=0,006) was a strong significant predictor of PFS. A lower overall survival was observed in the high NLR and PLR subgroup without significant differences (Long Rank, Mantel-Cox 1,245, p= 0,265; 0,578, p=0,447). No significant differences were obtained in any of the subgroups analysis regarding pCR rates. Purpose or Objective INTRODUCTION