The Prognostic Value of the Systemic Immune-Inflammation Index (SII) and Red Cell Distribution Width (RDW) in Patients with Cervical Cancer Treated Using Radiotherapy.

Abstract

There is growing interest in the prognostic value of routinely performed pre-treatment blood test indices, such as the RDW or SII, with the latter combining the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR). These indices were shown to be prognostic for survival in some malignancies. The purpose of this study was to evaluate the association between pre-treatment RDW and SII, and OS in patients treated with radiotherapy for primary localised cervical cancer. This retrospective analysis included patients treated with definitive CRT between 2011 and 2017 for histopathologically confirmed FIGO 2018 stage IB2-IVA cervical cancer. Statistical analysis was performed using the Kaplan-Meier method, two-sided log-rank tests, and Cox proportional hazards models, with the AIC serving as a prediction error estimator. The study group included 249 patients with a median age of 57.2 years and a median follow-up of 75.8 months. The majority were diagnosed with squamous cell carcinoma (237; 95.2%) and had FIGO stage III (211; 84.7%). Approximately half of the patients (116; 46.4%) had regional lymph node metastases. Patients with a low RDW (≤13.4%) and low SII (≤986.01) had a significantly longer OS (p = 0.001 and p = 0.002). The RDW remained as an independent prognostic factor in the multivariable model (high vs. low; HR = 2.04; 95% CI: 1.32-3.16; p = 0.001). Including RDW in the model decreased the Akaike Information Criterion from 1028.25 to 1018.15. The RDW is a cheap and widely available index that is simultaneously an independent prognostic factor for survival and could be used to improve pre-treatment prognosis assessments in patients with cervical cancer undergoing CRT. Available data encourage assessing the RDW as a prognostic factor in prospective trials to aid the identification of candidates for treatment escalation.