BackgroundThis study aimed to investigate the influence of immunonutritional factors on treatment-related toxicities and survival outcomes in patients with cervical cancer undergoing definitive radiochemotherapy. MethodsPatients with cervical cancer who received curative radiochemotherapy between 2016 and 2021 were retrospectively investigated. Pretreatment prognostic nutritional index (PNI), neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR), and platelet-lymphocyte ratio (PLR) were measured. Survival outcomes, acute and late toxicities were evaluated. ResultsAmong the 138 patients, those with larger tumor diameters had significantly lower pre-treatment PNI (p = 0.005). Pre-treatment immunonutritional factors were predictive of clinical survival, whereas post-treatment factors did not correlate with prognosis. Patients with low pre-treatment PNI (<49.5) or high NLR (>2.4) had shorter progression-free survival (PFS, HR: 1.86, p = 0.045 for PNI; HR: 3.15, p = 0.002 for NLR) and overall survival (OS, HR: 1.80, p = 0.048 for PNI; HR: 3.83, p = 0.015 for NLR). High pre-treatment NLR was associated with an increased risk of acute diarrhea (p = 0.049) and late severe toxicities (p = 0.046). Combined analysis revealed that pre-treatment good nutritional status and low systemic inflammation were linked to longer PFS (p = 0.007) and OS (p = 0.002), and poor nutritional status and substantial systemic inflammation were associated with higher rates of late severe toxicities (p = 0.036), with higher prognostic value in advanced stage patients. ConclusionPretreatment immunonutritional measures serve as quantitative biomarkers for predicting survivals and treatment toxicities in patients with cervical cancer treated with definitive radiochemotherapy.