Ultra-Low Risk Prostate Cancer Treated with Cryotherapy versus Radiation Therapy

Abstract

Cryotherapy and radiation therapy are definitive local treatment approaches for prostate cancer. There is both prospective and retrospective data for definitive radiotherapy, but the use of cryotherapy has been limited primarily to single arm single institutional retrospective studies. The American Urological Association asserts that definitive cryotherapy has a role in low risk disease. Per the NCCN guidelines, ultra-low risk prostate cancer patients are candidates for active surveillance as a viable monitoring approach, but some of these patients insist on proceeding with definitive therapy. We undertook a retrospective analysis of the most favorable subset of prostate cancer patients, with ultra-low risk disease, to comparatively elucidate the utility of radiotherapy and cryotherapy. Institutional Review Board approval was obtained prior to conducting a retrospective chart review of patients treated at our institution from 1999-2014 with external beam radiation therapy (EBRT), low dose rate brachytherapy (LDR), and cryotherapy. Patients meeting inclusion criteria for the present study were diagnosed with prostate cancer and had ultra-low-risk disease as defined by all of the following conditions: stage T1c TNM classification, PSA < 10, and a combined Gleason score of 3+3, 1-3 cores positive with no more than 50% of an individual core involved by tumor. Only patients who received definitive LDR, EBRT or cryotherapy monotherapy were included in the analysis. We excluded patients who were treated with radiation for surgical salvage. Disease specifics and failure details were collected for all patients. Failure was defined as PSA nadir +2ng/mL Sixty-five patients were treated with radiation (39 with EBRT and 26 with LDR), while 40 patients were treated with cryotherapy, The EBRT dose median was 75Gy (range: 72.0-79.2Gy). LDR patients were treated with 120Gy Pd-103 or 140-145Gy I-125 implant. All cryotherapy patients were treated with 2 freeze and thaw cycles. Median cores positive were 1 (range 1-3). Ninety percent of men had unilateral disease with 10% having bilateral disease. A median of 10% maximum volume of cores were positive (range: 1-50%). Mean PSA density was 0.11ng/mL/gm (range 0.09-0.14). Mean PSA follow-up was 57.3 and 51.5 months in the radiotherapy and cryotherapy groups respectively. Eighty-nine percent (58/65) and only 67.5% (13/40) of the cryotherapy patients were free of biochemical progression (p=0.0125). There was no difference in bPFS between EBRT an LDR (p=1.0). Time to biochemical progression in failed patients was 62 months in the radiotherapy group and 11 months in the cryotherapy group. In our practice, patients undergoing definitive treatment for ultra-low risk prostate cancer appear to do better with radiation therapy than cryotherapy. We likewise do not recommend cryotherapy as definitive treatment upfront for prostate cancer.