Plasma Calcitonin Gene-Related Peptide (CGRP) Levels in Patients With Head and Neck Malignancies Undergoing Radiotherapy

Radiotherapy-related pain is a major clinical challenge that significantly affects the long-term quality of life and treatment adherence of patients with head and neck cancer. Current analgesic strategies offer limited efficacy, and reliable biomarkers for predicting pain risk are lacking. In recent years, calcitonin gene-related peptide (CGRP) has drawn increasing attention for its critical role in chronic pain regulation, as demonstrated in various pain models. However, no systematic studies have yet investigated the expression patterns and clinical relevance of CGRP in radiotherapy-induced pain among patients with head and neck malignancies. This single-center, prospective observational study aims to enroll patients with head and neck cancer receiving either definitive or postoperative adjuvant radiotherapy. Plasma samples will be collected before, during, and after radiotherapy for measurement of CGRP levels. Pain intensity will be simultaneously assessed using the Numeric Rating Scale (NRS) and the Brief Pain Inventory-Short Form (BPI-SF). The study seeks to explore the dynamic changes in plasma CGRP levels throughout the radiotherapy course and to analyze their correlation with patient-reported pain, thereby providing potential insights into biomarker-based pain prediction and management strategies in this patient population.