Biopsy Assessment of Oncologic Control 3 Years Following Primary Partial Gland Cryoablation: A Prospective Cohort Study of Men With Intermediate-risk Prostate Cancer.

PURPOSE

We evaluated 3-year oncologic outcomes following primary partial gland cryoablation.

MATERIALS AND METHODS

Men with unilateral intermediate-risk prostate cancer undergoing primary partial gland cryoablation since March 2017 enrolled in a prospective outcome registry. The postablation protocol for all men included surveillance prostate biopsy at 2 years postablation and reflex prostate biopsy for cases with high suspicion of recurrence (eg, progressive rise in PSA). Recurrence of clinically significant prostate cancer was defined as any Gleason grade group ≥2 disease on postablation biopsy. Freedom from failure represented no whole gland salvage treatment, metastatic prostate cancer, or prostate cancer mortality. Freedom from recurrence and freedom from failure were characterized using nonparametric maximum likelihood estimators.

RESULTS

A total of 132 men had at least 24 months of follow-up data. Biopsies identified clinically significant prostate cancer in 12 men. At 36 months, model-estimated rates of freedom from recurrence of in-field, out-of-field, and overall clinically significant cancer were 97% (95% CI: 92-100), 87% (95% CI: 80-94), and 86% (95% CI: 78-93), respectively. The model-estimated proportion with freedom from failure at 36 months was 97% (95% CI: 93-100).

CONCLUSIONS

The low in-field cancer detection rate at 3 years indicates successful ablation of localized cancers. Conversely, our observed out-of-field detection rate highlights the need for continued surveillance following partial gland cryoablation. Many of these recurrences exhibited very low volume of clinically significant disease below the detection threshold of multiparametric MRI, suggesting a limited role for multiparametric MRI in detecting clinically significant recurrences at 2 years. These findings emphasize the need for long-term surveillance and identification of predictors of clinically significant prostate cancer recurrences to guide biopsy timing.