PSA Bounce After Dose-Escalated External Beam Radiation Therapy Is an Independent Predictor of PSA Recurrence, Metastasis, and Survival in Prostate Adenocarcinoma Patients
Menée auprès de 776 patients atteints d'un adénocarcinome de la prostate traité par radiothérapie externe avec escalade de doses en combinaison avec un traitement anti-androgénique concomitant ou néo-adjuvant (durée médiane de suivi : 9,2 ans), cette étude met en évidence une association entre une élévation transitoire du niveau du PSA après la radiothérapie et le risque de récidive biochimique ou de métastases ainsi que la survie des patients
Purpose : Post-treatment PSA bounce (PSA-B) is well recognized and reported in 15%-30% of prostate adenocarcinoma patients treated with radiotherapy. We evaluated the difference in PSA recurrence-free (PSA-RFS), distant metastasis–free (DMFS), overall (OS), and cancer-specific (CSS) survival between PSA bounce (PSA-B) and non-bounce patients treated with dose-escalated external beam radiotherapy (DE-EBRT).
Materials/Methods : During 1990-2010, 1898 prostate adenocarcinoma patients were treated with DE-EBRT to ≥75 Gy with ≥5 years follow-up. Patients receiving neoadjuvant/concurrent androgen-deprivation therapy (n=1035) or with less than four PSA values obtained 6 months or more after post-EBRT completion (n=87) were excluded. The evaluable 776 patients were treated (median, 81.0 Gy). PSA-B was defined as a ≥0.2 ng/mL increase above the interval PSA nadir followed by a decrease to nadir or below. PSA relapse (PSA-R) was defined as post-RT PSA nadir + 2 ng/mL. Median follow-up was 9.2 years (IQR, 5.3-10.6 years).
Results : One hundred twenty-three patients (15.9%) experienced PSA-B after DE-EBRT at a median of 24.6 months (IQR, 16.1-38.5 months). On multivariate analysis, younger age (P=0.001), lower Gleason score (P=0.0003), and higher RT dose (P=0.0002) independently predicted PSA-B. PSA-B was independently associated with decreased risk for PSA relapse (HR, 0.53; 95% CI, 0.33-0.85; P=0.008), distant metastatic disease (HR, 0.34; 95% CI, 0.12-0.94; P=0.04), and all-cause mortality (HR, 0.53; 95% CI, 0.29-0.96; P=0.04) on multivariate Cox analysis. As all 50 prostate cancer–specific deaths in patients without PSA-B were in the non-bounce cohort, competing-risks analysis was not applicable. Nonparametric competing-risks test demonstrated that patients with PSA-B had superior cancer specific survival compared to patients without PSA-B (P=0.004)
Conclusions : Patients treated with dose-escalated radiotherapy for prostate adenocarcinoma who experience post-treatment PSA-B have improved PSA-RFS, DMFS, OS, and CSS outcomes.
International Journal of Radiation Oncology • Biology • Physics , résumé, 2016