Abstract
Objective
Whole gland treatment of the prostate has known efficacy in treating many grades of prostate cancer. However, it is often associated with increased morbidity, including erectile dysfunction and urinary incontinence. Focal ablative therapies, including focal cryoablation (FC), are utilized to minimize the risk of tumor progression and preserve erectile and urinary function. There is little to no consensus on whether intermediate or high-risk prostate cancer should be treated with focal therapy. However, there is a growing body of literature on the effectiveness of FC as an effective means of prostate cancer control. We characterize our experience with 163 patients who underwent FC with a median follow-up of 39 months (IQR: 24-60).
Methods
A 163-patient retrospective cohort underwent FC of the prostate at a single clinic by a physician from November 2008 to December 2020. Each of these T1c patients in this single-tail study was monitored for biochemical recurrence (BCR) and oncologic outcomes. American Society for Radiation Oncology (ASTRO) definition of BCR is three consecutive prostate-specific antigens (PSA) increases of more than 0.5 ng/mL or, along with the utilization of the Phoenix definition, a PSA greater than nadir by 2 ng/mL was used to define BCR. This study's primary endpoint includes BCR or biochemical disease-free survival rates. Secondary endpoints include patient side effects, such as measuring for urinary incontinence and outcomes of salvage treatments. Cox proportional hazard analyses defined univariate HRs and 95% CIs for pre-operative PSA (POPSA), Decipher, and Gleason Grade Groups (GGGs) to determine the prognostic impact of pathologic factors. Statistical analysis and BCR timeline analysis also included logistic regression and the Kaplan-Meier method, with significance considered at p < 0.05. Select focal cryotherapy patients were monitored utilizing genomic sequencing tests.
Results
Our cohort included 27 patients (16.5%) with D'Amico low, 115 patients (70.5%) with intermediate, and 23 patients (14.1%) with high-risk prostate cancers. One month after FC, a 73% reduction in PSA resulted in a median post-operative PSA of 1.39 ng/mL (IQR: 0.46-2.80 ng/mL). At five years, our cohort yielded biochemical disease-free recurrence rates of 78%, 74%, and 55% for low, intermediate, and high-grade cancers, respectively. Genetic risk stratification results showed very similar BCR rates to patients whose tissues did not undergo genomic testing, at 27%, 26%, and 46% for low, intermediate, and high-grade cancers, respectively. Log-rank tests to map for BCR and HRs for pathologic factors did not yield any statistically significant predictive results. Urinary incontinence and erectile dysfunction were reported in 1.8% and 3.1% of patients in the focal cohort.
Conclusions
Our results add to the expanding body of literature around the efficacy of focal ablative therapies in contrast to whole gland treatment. The definitive extent of FC's efficacy still remains to be explored, but our conclusions demonstrate favorable PSA kinetics at five years follow-up.