Focal Therapy: A New Paradigm for the Treatment of Prostate Cancer

Focal therapy has been proposed in recent years as a means of bridging the gap between radical prostatectomy and active surveillance for treatment of prostate cancer. The rationale for focal therapy comes from its success in treating other malignancies. One of the challenges in applying such an approach to the treatment of prostate cancer has been the multifocal nature of the disease. This review addresses the selection of potentially ideal candidates for focal therapy and discusses which modalities are currently being used and proposed for focal therapy. Setting and meeting guidelines for oncologic efficacy is a challenge we must embrace to safely deliver this potentially revolutionary approach to treating men with prostate cancer.Key words: Focal therapy, Photodynamic therapy, Prostatic neoplasms, Prostate-specific antigen, Prostatectomy, Ultrasound, high-intensity focused, transrectal, CryosurgeryWith the advent of prostate-specific antigen (PSA) screening there has been a stage migration, with radical prostatectomy (RP) being performed with increasing frequency in men with low-risk disease.¹ Whole gland treatment of prostate cancer carries a significant risk of incontinence and sexual dysfunction. Even in the most experienced centers, the rate of potency following RP is approximately 60%.^2–4 Stage migration has led many to recommend active surveillance (AS) as a means to decrease the number of men who may be overtreated; however, AS has been slow to gain acceptance in the United States.An analysis of over 5300 men from the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) National Prostate Cancer Registry⁵ showed that only 7% of men with clinically localized prostate cancer chose AS as an initial option. Aside from the anxiety that stems from not treating a diagnosed cancer, the greater difficulty with AS lies in selection of candidates and appropriate parameters for surveillance, allowing prompt intervention without compromising cure rates.Focal therapy has been proposed in recent years as a means of bridging the gap between whole gland treatment and AS. Many believe that for patients with low-risk disease, focal therapy is the ideal option for maximizing quality of life by avoiding the effects of whole gland radiation or surgery while alleviating the anxiety and uncertainty of AS. The definition of focal therapy itself is not well established and includes lesion-targeted therapy (LAT), hemiablative therapy (HAT), or subtotal gland therapy (STAT), sparing at least 1 neurovascular bundle.⁶The rationale for focal therapy comes from its success in treating other malignancies. In breast cancer treatment, for example, radical mastectomy has been replaced in many instances by local excision and Mohs surgery has led to less radical surgery for the treatment of melanoma.⁷ In our own field, the push for nephron-sparing surgery has led to the favoring of partial nephrectomy in tumors less than 7 cm, with oncologic outcomes similar to those of radical nephrectomy.⁸The challenge in applying such an approach to the treatment of prostate cancer has been the multifocal nature of prostate cancer and the fact that most cancers are detected without identifying a lesion on palpation or imaging studies.^9,10In this review, we revisit the current status of focal therapy in the treatment of prostate cancer. We discuss whether there are ideal candidates for focal therapy; we then discuss how these candidates should be selected. We review which modalities are currently being used and proposed for focal therapy. Finally, we discuss potential definitions of successful treatment. As this article shows, there are still many aspects of focal therapy that are yet to be defined, that warrant a great need for further research.