Background. Definitive chemoradiotherapy represents the standard therapeutic approach for the management of locally advanced cervical cancer. Vitamin D plays an important role in the regulation of cellular growth and differentiation, immune system function, and the modulation of inflammatory processes. Hypovitaminosis D may be associated with the development of cervical cancer, whereas its impact on the effects of oncological treatment remains insufficiently elucidated. The aim of this study is to investigate the predictive significance of vitamin D in patients with locally advanced cervical cancer treated with definitive chemoradiotherapy.

Methods. This study is designed as a clinical, observational, prospective cohort study. Patients with locally advanced cervical cancer undergoing definitive chemoradiotherapy at the Clinic for Radiation Oncology, University Clinical Center Kragujevac, will be enrolled. Vitamin D concentrations will be measured before the initiation of treatment in both serum and cervical lavage samples. Baseline vitamin D levels will be analyzed in relation to treatment outcome and the occurrence of acute radiation toxicity. In addition, vitamin D concentrations will be evaluated in the context of clinical and morphological parameters, therapeutic response, and treatment-related toxicity.

Expected Results. This study will enable an assessment of the actual significance of pretreatment vitamin D concentrations in serum and cervical lavage as a potential novel biomarker in relation to chemoradiosensitivity and/or chemoradioresistance of cervical cancer, as well as the response of organs at risk, in patients with locally advanced disease.