Does lower dose pilocarpine have a role in radiation-induced xerostomia in the modern radiotherapy era? A single-center experience based on patient-reported outcome measures.

Abstract

This study aims to investigate the efficacy of lower dose pilocarpine in alleviating late dry mouth symptoms in head and neck cancer patients received radiotherapy. Eighteen head and neck cancer patients experiencing persistent dry mouth were enrolled in this study. All participants started pilocarpine treatment a median of 6months post-radiotherapy. Initially, patients received pilocarpine at 5mg/day, with a gradual increase to the recommended dose of 15mg/day. A Patient-Reported Outcome Measurement (PROMs) questionnaire assessed symptoms' severity related to hyposalivation. All patients reported symptomatic dry mouth above grade 2 before starting the medication. Pilocarpine treatment continued based on patients' self-assessment, with a median duration of 12months (range, 3-36months). The median daily maintenance dose was 10mg (range, 5 to 20mg). Total PROMs scores significantly decreased following medication, from 13 points (range 7-18 points) to 7 points (range 4-13 points) (p = 0.001). Significant improvements were observed in questions related to dry mouth (p < 0.001), water intake during eating (p = 0.01), carrying water (p = 0.01), taste (p < 0.001), and water intake during speech (p < 0.001). Initial and maintenance doses of pilocarpine were lower, and the duration of pilocarpine usage was shorter in patients treated with intensity-modulated radiation therapy compared to conformal radiotherapy (12months vs. 25months, p = 0.04). Pilocarpine may be considered at doses lower for late-term dry mouth. With modern radiotherapy techniques effectively preserving the parotid gland, short-term use may be recommended in these patients. Future studies may enhance the development of a more robust patient selection criteria model.