COMMENTARY

Piloting Focal Therapy in Prostate Cancer

Hossein Jadvar, MD, PhD, MPH, MBA

Disclosures

January 03, 2018

A New Option in Localized Prostate Cancer?

Prostate cancer is a major public health problem in the United States, affecting about 1 in 6 men. In patients with low- to intermediate-risk prostate cancer, focal therapy (male lumpectomy) has been advocated as a viable gland-preserving treatment strategy, falling somewhere on the management spectrum between active surveillance and whole-gland definitive therapy.[1,2]

Imaging is essential at many decision points in the management of localized prostate cancer with focal therapy. These decisions include patient selection, choice of focal therapy, assessment of treatment efficacy, and potential need for focal retreatment or radical therapy.[3]

The Study

Tay and colleagues[4] from Singapore General Hospital and the National Cancer Center in Singapore investigated the safety profile and 2-year functional outcomes of in-bore magnetic resonance (MR)-guided focused ultrasound therapy in 14 men with low-volume, low-grade prostate cancer, with up to two primary foci (clinical stage T2a or lower, Gleason score 3+3, index tumor ≤ 10 mm3). Mean sonification (achieving temperatures of 60°-85°C for focal tissue coagulation) focal therapy time was 117 ± 50 minutes, and the mean total time in the MR scanner was 267 ± 55 minutes.

The mean prostate-specific antigen (PSA) level before therapy was 8.3 ± 4.0 ng/mL, and 12 men completed the 2-year follow-up period. Six months after therapy, mean PSA levels were 2.9 ng/mL lower (median reduction of about 39% within 3 months). There was no statistically significant change in urinary symptoms or sexual function. At the 6-month template biopsy, one patient had cancer with a Gleason score > 6. At 24 months, three men had cancer with a Gleason score > 6.

Viewpoint

Focal therapy may gain traction in the care of men with low- to intermediate-grade, low-volume prostate cancer. This option may attract patients who have declined radical treatment owing to its well-known risks but who seek a more proactive approach than active surveillance.

Male lumpectomy is reminiscent of breast lumpectomy in women with localized breast cancer who undergo breast-preserving surgery. However, the case for the prostate gland is challenging, given its smaller size and frequent multifocal cancer sites. Moreover, long-term outcome data on this conservative type of treatment are lacking compared with standard radical treatment.

In this new pilot study, Tay and colleagues demonstrate that MR-guided, focused, ultrasound-induced heat coagulation therapy can be delivered safely and can be monitored immediately afterward with MR imaging to assess tumor ablation coverage.

Only two of 12 patients with complete follow-up data had tumors with a Gleason score > 6 during the 2-year follow-up. From these data, it is unclear whether the cases represented de novo tumor sites, underestimation of primary cancer before focal therapy, or failure of focal ablation. Further investigations are needed to stratify patients who would benefit most from focal therapy, to accurately assess efficacy, determine the decision point for retreatment versus transition to whole-gland therapy, and predict short-term and long-term outcomes.

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