Four-year outcomes from a prospective phase II clinical trial of moderately hypofractionated proton therapy for localized prostate cancer
Mené sur 184 patients atteints d'un cancer de la prostate de stade localisé et à risque faible ou intermédiaire de récidive (durée médiane de suivi : 49,2 mois), cet essai de phase II évalue la toxicité gastro-intestinale et urologique d'une protonthérapie avec hypofractionnement modéré
Résumé en anglais
Background : Moderately hypofractionated radiation therapy represents an effective treatment for localized prostate cancer (PC). While large randomized trials have shown the efficacy of photon-based hypofractionated therapy, hypofractionated proton therapy (HFPT) has not been extensively studied. This study was performed to determine the clinical and patient-reported outcomes for patients with PC treated with HFPT.
Methods : Between 2010 and 2017, 184 men were enrolled on a trial of 70Gy in 28 fractions of HFPT for low to intermediate-risk PC. Acute and late toxicity was evaluated using CTCAEv4.0. Patient reported outcomes were measured by International Prostate Symptom Score (IPSS), International Index of Erectile Function (IIEF-5) Questionnaire, and Expanded Prostate Cancer Index Composite (EPIC) scores.
Results : Median follow-up was 49.2 months. Enrolled patients had low-risk [LR] (n = 18), favorable intermediate-risk [FIR] (n = 78), and unfavorable intermediate-risk [UIR] (n = 88) PC. Four-year rates of BCF free survival were 93.5% (95% C.I. 89-98%), 94.4% (89-100%), 92.5% (86-100%), and 93.8% (88-100%) in the overall group and the LR, FIR, and UIR cohorts, respectively (logrank p>0.4). The incidence of acute grade 2 or higher gastrointestinal (GI) and urologic toxicities were 3.8% and 12.5%, respectively. The 4-year incidence of late grade 2 or higher urologic and GI toxicity was 7.6% (4-13%) and 13.6% (9-20%), respectively. One late grade 3 GI toxicity was reported. All late toxicities were transient. Patient reported IPSS, IIEF, and EPIC scores had no significant long term changes following completion of HFPT.
Conclusions : HFPT is associated with low rates of toxicity and does not appear to negatively impact 4-year patient reported urinary and bowel health. Further comparative analyses are warranted to better understand differences between proton and photon HFRT.
