Pathologic Assessment and Implications Following Focal Therapy of Prostate Cancer

Focal therapy represents a new paradigm in the management of prostate cancer. The application of focal therapy results, by definition, in the division of the prostate into two distinct areas namely a treated and an untreated zone. Biopsy interrogation of both areas is becoming an integral part of the follow-up of patients treated with focal therapy. Adequate interpretation of these samples requires an intricate knowledge of the morphologic changes associated with the emerging therapeutic modalities, including brachytherapy, high-intensity focused ultrasound, cryotherapy, laser ablation, photodynamic therapy, irreversible electroporation, interstitial microwave thermal therapy, and radiofrequency interstitial tumor ablation. Expected findings for these therapeutic modalities are summarized herein. Additionally, the nontreated area would require active surveillance, the parameters of which are still under development. The pathologist plays a significant role in the definition of criteria for success and failure in this new clinicopathological setting.