Curative Radiotherapy at Time of Progression Under Active Surveillance Compared with Upfront Radical Radiotherapy for Prostate Cancer
Menée à partir de données portant sur 1 070 patients atteints d'un cancer de la prostate et bénéficiant d'une surveillance active (durée médiane de suivi : 4,9 ans), cette étude évalue, du point de vue du taux de récidive biochimique, de l'absence de métastases et de la survie globale, la possibilité de différer une radiothérapie curative
Purpose : Active surveillance (AS) is a common management strategy for presumed indolent prostate cancer. However, limited evidence suggest it does not compromise outcomes in those who progress and subsequently undergo radical treatment. We compared outcomes in men receiving definitive radiotherapy following AS with those in a risk-matched cohort undergoing upfront radiotherapy. Methods and Materials : Men prospectively enrolled in an AS program between 1992-2014 and subsequently undergoing curative radiotherapy (i.e. image-guided radiotherapy [IGRT] or brachytherapy [LDR-BT]) were identified. Biochemical relapse-rates (bRFR), metastasis-free rates (mFR), and overall survival (OS) were compared against a cohort of men treated upfront; matched by age, clinical prognostic indices (risk-group, PSA, cT-category, Gleason score, percentage of involved biopsy cores), and radiotherapy modality. Results : Of 1070 patients in the AS registry, 200 underwent definitive RT (143 IGRT and 57 LDR-BT) after a median of 32.9 (IQR 20.6 - 59.8) months on surveillance. Main reasons for treatment were grade and volume upgrading (57.5% and 26% respectively). Median follow-up post RT was 4.9 years (IQR 3.1-7.5). At 5-years, the bRFR, mFR and OS were respectively 97%, 99%, 98.5%. No patient died of prostate cancer. Adequate risk-matching was confirmed in an independent cohort comprising 359 patients receiving upfront IGRT (71%) or LDR-BT (29%), and followed for a median of 9 years (IQR 3.1-7.5). There was no difference in the disease-specific outcomes (bRFR, mFR) between the two cohorts (Gray´s p-value 0.257 and 0.934, respectively). In multivariate-analyses, timing of radical RT (deferred vs upfront) was not correlated to biochemical relapse nor metastases occurrence. Conclusions : Curative-intent radiotherapy (i.e. dose-escalated IGRT or LDR-BT) after a period of AS renders excellent oncologic outcomes at 5 years. Deferring radical therapy after a period of AS does not appear to result in inferior oncologic outcomes compared to patients with similar risk characteristics undergoing upfront treatment.