Hyperbaric oxygen therapy for radiation-induced cystitis: a prospective study using the portuguese navy radiation-induced cystitis scale

Background: Radiotherapy (RT) is a cornerstone of multidisciplinary cancer treatment and is administered to a substantial proportion of oncology patients worldwide.Objectives: The primary objective of this study was to validate the clinical applicability of the Portuguese Navy Radiation-induced Cystitis (PNRC) scale for grading the severity of radiation-induced cystitis (RC) and for monitoring response to hyperbaric oxygen therapy (HBOT).Methods: In this single-center cohort, the PNRC scale was prospectively applied over three years in patients with RC treated with HBOT, using retrospectively collected clinical data.Descriptive and inferential statistics were used to explore the association between changes in PNRC grade, macroscopic hematuria resolution, and selected clinical and treatment-related variables, with statistical significance set at p < 0.05.A multivariate logistic regression model was fitted to identify independent predictors of major response, defined as a reduction of at least three PNRC grades.Results: Ninety-four patients were included (mean age 71.7 years; 87.2% male; 85.1% prostate cancer).After a mean of 41.7 (10-120) HBOT sessions, the overall response and disease control rates were 84.1% and 98.9%, respectively, and macroscopic hematuria resolved in 83.7% of evaluable patients.More than half of the cohort improved by at least two PNRC grades, and 34.0%achieved a major response (≥ 3-grade reduction).In multivariate analysis, age ≥ 75 years showed the strongest association with major response (adjusted odds ratio 2.51, 95% CI 1.00-6.33;p = 0.051), whereas no other variable demonstrated an independent effect.HBOT was well tolerated, with complications in 17.0% of patients, predominantly middle-ear barotrauma (13.8%), and an RC recurrence rate of 8.5% over a median follow-up of 5 months.Conclusion: HBOT was effective and safe for the management of RC in this cohort, and the PNRC scale proved to be a practical tool for grading disease severity and capturing clinically meaningful changes in response to treatment.The scale may also help identify patients more likely to benefit from HBOT, supporting its broader integration into routine clinical practice.