PSA kinetics following primary focal cryotherapy (hemiablation) in organ-confined prostate cancer patients.

Abstract

We aim to evaluate prostate-specific antigen (PSA) trends in post-primary focal cryotherapy (PFC) patients. This was an institutional review board-approved retrospective study of PFC patients from 2010 to 2015. Patients with at least one post-PFC PSA were included in the study. Biochemical recurrence (BCR) was determined using the Phoenix criteria. PSA bounce was also assessed. We analyzed rates of change of PSA over time of post-PFC between BCR and no BCR groups. PSA-derived variables were analyzed as potential predictors of BCR. A total of 104 PFC patients were included in our analysis. Median (range) age and follow-up time were 66 (48-82) years and 19 (6.3-38.6) months, respectively. Four (3.8%) patients experienced PSA bounce. The median percent drop in first post-PFC PSA of 80.0% was not associated with BCR (p=0.256) and may indicate elimination of the index lesion. The rate of increase of PSA in BCR patients was significantly higher compared to patients who did not recur (median PSA velocity (PSAV): 0.15 vs 0.04ng/ml/month, p=0.001). Similar to PSAV (HR 9.570, 95% CI 3.725-24.592, p<0.0001), PSA nadir≥2ng/ml [HR (hazard ratio) 1.251, 95% CI 1.100-1.422, p=0.001] was independently associated with BCR. A significant drop in post-PFC PSA may indicate elimination of the index lesion. Patients who are likely to recur biochemically have a significantly higher PSAV compared to those who do not recur. Nadir PSA of less than 2ng/ml may be considered the new normal PSA in focal cryotherapy (hemiablation) follow-up.