Post-operative radiation therapy for prostate cancer: Comparison of conventional versus hypofractionated radiation regimens
Menée auprès de 461 patients atteints d'un cancer de la prostate traité par prostatectomie entre 2005 et 2016 (durée médiane de suivi : 38,6 mois), cette étude multicentrique compare l'efficacité, du point de vue de la survie sans progression biochimique, et la toxicité d'une radiothérapie hypofractionnée et d'une radiothérapie conventionnelle
Purpose/Objectives : Post-prostatectomy radiotherapy (PORT) for adverse pathologic factors results in improved overall and biochemical progression-free survival. Conventional PORT (coPORT) is delivered over 7-8 weeks. Hypofractionated PORT (hypoPORT) offers a more resource-efficient option if shown to have acceptable efficacy and toxicity compared to coPORT. We compared acute/late toxicity and biochemical control in contemporaneous patient cohorts treated with hypoPORT or coPORT. Methods/Materials : Consecutive patients treated with intensity-modulated hypoPORT (2.5 Gy/fraction, median cumulative dose 65 Gy [range 57.5-70 Gy]) or coPORT (1.8-2.0 Gy/fraction, median cumulative dose 66 Gy [range 60-74 Gy]) between 2005-2016 at two institutions comprised the study cohort. Acute toxicity, cumulative late grade 2 and ≥3 GU and GI toxicity incidences (CI) were calculated for all patients using the Kaplan-Meier methods and compared between cohorts. Biochemical progression free survival (bPFS) was calculated in patients with ≥12 months follow-up (FU) Results : Median FU for all 461 patients was 38.6 months. 167 (36%) received hypoPORT; 294 (64%) patients received coPORT. The hypoPORT cohort had significantly worse baseline urinary incontinence. Acute grade ≥2 GU toxicity was more common after hypoPORT (22% vs 8%) (p=0.0001). Late grade ≥3 GU toxicity CI at 6 years was 11% (hypoPORT) and 4% (coPORT) (p=0.0081). However, hypoPORT was not associated with late grade ≥2 GU toxicity on MVA (HR 1.39, 95% CI 0.86-2.34) (p=0.18). There was no difference in acute or late GI toxicity. In the subset of patients with ≥12 month FU (n=364, median FU 52 months) 4-year bPFS was 78% (95% CI 69.4-85.0%) after hypoPORT (p=0.0038) and 65% (95% CI 57.6-71.1%) after coPORT. HypoPORT was not significant for bPFS on MVA (HR 0.64 95% CI 0.41-1.02, p=0.059). Conclusions : HypoPORT shows promising early biochemical control. After controlling for baseline urinary function, hypoPORT was not associated with greater GU toxicity than coPORT.