Main Session
Sep
29
PQA 06 - Genitourinary Cancer, Gynecological Cancer, and Health Care Access and Engagement
3245 - Physician and Patient Reported Outcomes Following Contemporary Image-Guided Intensity Modulated Proton Therapy for Prostate Cancer: Results from the Prospective PRO-Cube Study
Presenter(s)
Srinivas Chilukuri, MD, MBBS - Apollo Proton Cancer Centre, Chennai, Tamil Nadu
S. Chilukuri1, S. Sundar2, M. Arjuna3, A. Sinha4, R. Kamath4, P. K. Panda4, D. Shamurailatpam5, and R. Jalali4; 1Department of Radiation Oncology, Apollo Proton Cancer Center, Chennai, Chennai, India, 2Department of Radiation Oncology, Apollo Proton Cancer Centre, Chennai, India, 3Department of Medical Physics, Apollo Proton Cancer Center, Chennai, Chennai, India, 4Apollo Proton Cancer Centre, Chennai, India, 5Department of Medical Physics, Apollo Proton Cancer Centre, Chennai, India
Purpose/Objective(s):
Multiple prospective studies have established the safety of proton therapy for localized prostate cancer. However, prospective data defining toxicity and patient-reported outcomes with contemporary image-guided intensity-modulated proton therapy (IG-IMPT) in high-risk and node-positive disease treated with hypofractionation, including extreme hypofractionation (SBPT) and pelvic nodal irradiation (PNI), remain limited. We report prospectively collected physician-reported adverse events, patient-reported outcomes, and early clinical outcomes from the PRO-Cube registry.Materials/Methods:
PRO-Cube is a prospective, single-centre registry enrolling men with prostate cancer treated with IG-IMPT across all risk groups and fractionation schedules with or without PNI. This analysis includes 155 consecutive patients treated definitively using daily cone-beam CT–guided IG-IMPT and robust optimization. Physician-reported GU and GI AEs were prospectively graded using CTCAE v5.0, and PROs were longitudinally assessed using EORTC QLQ-PR25 with mixed-effects linear models to characterize temporal symptom trajectories and minimally clinical important difference (MCID).Results:
Median age was 70 years (IQR, 62–75); 73.6% had high- or very-high-risk disease, including 24.5% node-positive. SBPT was used in 46.5%, PNI in 60%, and androgen deprivation therapy in 87.1% of patients. With a median follow-up of 35.8 months (IQR, 24–52), acute grade =2 GU AEs occurred in 23.9%, driven primarily by transient irritative urinary symptoms, while no acute grade =2 GI AEs were observed. Cumulative late grade =2 GU and GI AEs were infrequent, occurring in 5% and 4.3%, respectively. Severe late toxicity (grade =3) was rare (<1%). PRO trajectories demonstrated early post-treatment worsening in urinary and bowel symptoms followed by gradual improvement over time concordant with physician-reported AEs. MCID analyses showed that most patients remained stable over time. Using a =10-point threshold, approximately 75–86% of patients were stable for urinary symptoms and 95–100% for bowel symptoms at individual time points; =20-point deteriorations were uncommon. No patient, tumor, or treatment-related factors were associated with higher AEs or adverse PROs.Conclusion:
IG-IMPT demonstrated low rates of physician-reported AEs and favorable PRO trajectories, despite frequent use of hypofractionation and PNI in a predominantly high-risk and node-positive cohort. These findings establish a benchmark for modern IMPT practice and provide a rationale for prospective comparison with contemporary IMRT.