Long-term outcome of randomized trial between cryoablation and external beam therapy for locally advanced prostate cancer (T2C-T3B).

Abstract

78 Background: Our primary objective is to assess and compare the survival outcomes between cryoablation (CRYO) and external beam radiation therapy (EBRT) in locally advanced prostate cancer. Methods: This is a single institution, retrospective study. Our institution ethics board had approved this study. Patients were initially recruited for the trial between 1999 and 2002. The inclusion criteria for the trial were patients with cT2c–cT3b prostate cancer, PSA < 25ng/ml, with negative metastatic evaluation on CT and bone scan. Patients with evidence of metastasis, prior pelvic radiotherapy or hormone therapy, prostate volume > 75 ml or American Society of Anesthesiology Risk class > 3 were excluded. The biochemical failure was based on the Phoenix criteria (PSA nadir + 2ng/dl). Patients were subjected for regular trans-rectal ultrasound and biopsy until 24 months of follow-up (at 3, 6, 12, 18, 24 months for CRYO and at 18, 24 months for EBRT) and then as clinically indicated. Biochemical disease-free survival (bDFS), disease-specific survival (DSS) and overall survival (OS) were analyzed with Kaplan-Meier curve. Results: Sixty-two patients completed the trial with a median follow-up of 105.2 (± 35.8) months. Preoperative demographic and clinicopathological characteristics of both groups were comparable. All patients received neoadjuvant hormonal therapy for 3 months prior and continued for 3 months after the procedures. The prostate volume before the therapy was smaller in the CRYO group (31.3 ml vs 40.9 ml; p≤0.01). There was greater reduction in the prostate volume in the CRYO group after the intervention (–54% vs 34%; p≤0.01).Three patients in the cryotherapy arm and 2 patients in the radiotherapy arm were crossed over to the other modality at the time of biochemical or biopsy proven progression. The DSS and the OS were comparable between both groups. The 8-year bDFS rate was significant lower in the CRYO group (17.4% vs 59.1%; p=0.01). Conclusions: This randomized trial showed that CRYO was suboptimal in attaining bDFS at 8 years in patients with locally advanced prostate cancer (cT3). Other recent randomized trial showed favorable outcome with CRYO for localized prostate cancer. No significant financial relationships to disclose.