Oncological control following partial gland ablation for intermediate-risk prostate cancer

Historically, the primary objection to partial gland ablation (PGA) for management of prostate cancer (CaP) has been disease multifocality and inability to localize significant disease. Improved disease localization and risk stratification with multiparametric magnetic resonance imaging and targeted biopsy, along with its minimal adverse impact on quality of life has enabled PGA to gain acceptance. Today, the primary barrier for adopting PGA is its unknown oncological outcomes. Objectives of this review are to provide a rationale for PGA for managing intermediate-risk (IR) CaP; review oncological outcomes following PGA for IR disease; and assess whether there is adequate data to justify PGA for management of IR CaP. There is no consensus how to assess or define oncological outcomes following PGA. We propose the following definitions for oncological outcomes: Oncological control (detection of any cancer following biopsy), oncological failure (detection of Gleason grade group >1 on follow-up biopsy), and oncological treatment failure (any disease that precipitate salvage treatment). There are only 3 reports in the literature where inclusion criteria specified pretreatment targeted biopsy and reflex prostate biopsy within 1 year of PGA in cohorts of men where >50% had Gleason grade group >1 disease. These studies reported that prostate-specific antigen is not a reliable surrogate and multiparametric magnetic resonance imaging is reliable when prevalence of in-field CaP is high. "Freedom from failure" is used to assess longer-term oncologic outcomes, and is defined by freedom from CaP mortality, androgen deprivation therapy, or whole-gland treatment. Rationale for PGA in selected cases of IR CaP is compelling and early oncological studies are reassuring. If patient selection is done judiciously, oncologic outcomes are disclosed, and follow-up plan is rigorously implemented, it is unlikely rates of metastasis or CaP mortality with be adversely impacted and many men will avoid or defer adverse effects of whole-gland treatment.