A Real-World Evaluation of Health-Related Quality of Life Using the EQ-5D-5L Instrument in Patients Undergoing Radiotherapy for Prostate Cancer

Abstract

Background/aim: Prostate cancer (PC) is increasingly treated with curative intent, making health-related quality of life (HRQOL) a key outcome. This prospective study evaluated the EQ-5D-5L instrument based HRQOL trajectories in PC patients undergoing radiotherapy (RT) to assess the instrument's responsiveness, determine meaningful changes, and strengthen the evidence on patient-centered outcomes in routine care.

Patients and methods: A total of 262 patients undergoing curative RT were prospectively assessed using the EQ-5D-5L questionnaire at baseline, treatment completion, and final follow-up. HRQOL was evaluated using the health index (HI) and visual analogue scale (VAS), with clinically meaningful changes categorized according to validated minimal important difference (MID) thresholds. Multiple linear regression models were constructed to identify predictors of HI and VAS outcomes, with baseline HRQOL values emerging as the strongest determinants of post-treatment scores.

Results: The study cohort was stratified into primary, adjuvant, and salvage RT groups. Mean baseline HI scores were high across groups, ranging from 0.91 to 0.95, and remained stable or improved at follow-up. VAS scores demonstrated similar stability, with final follow-up values ranging from 77.0 to 83.0 across treatment groups. Hypofractionated patients showed superior HRQOL trajectories, with 40% HI and 80% VAS improvement at follow-up, compared to 25% and 29% in normofractionated patients, respectively. Longitudinal analyses revealed favorable HRQOL preservation, particularly in salvage RT, where HI improved from 0.93 to 0.96. Regression analysis confirmed baseline HRQOL values as the strongest predictors of both HI and VAS outcomes (p<0.001). Additional predictors included chronic toxicity and age, with consistent model validity confirmed through diagnostics. The extended models significantly outperformed basic models, with the best predictive performance seen for HI at the end of RT (adjusted R²=0.514).

Conclusion: The sustained HRQOL, particularly in adjuvant and salvage settings, supports the role of RT in multimodal strategies.

Keywords: EQ-5D-5L; Prostate cancer; health-related quality of life; questionnaire; radiation therapy.