Leonard S. Marks, MD, presented “Application of MRI Fusion Biopsy Results to Focal Therapy” during the Southwest Prostate Cancer Symposium 2020 virtual conference in December 2020.


How to cite: Marks, Leonard S. “Application of MRI Fusion Biopsy Results to Focal Therapy” December 2020. Accessed Jun 2021. https://grandroundsinurology.com/application-of-mri-fusion-biopsy-results-to-focal-therapy/

Application of MRI Fusion Biopsy Results to Focal Therapy – Summary:

Leonard S. Marks, MD, Professor and inaugural holder of the deKernion Chair in Urology at the David Geffen School of Medicine at the University of California, Los Angeles, discusses focal therapy using MRI fusion biopsy and a novel process to determine tumor margins. He outlines the rationale for focal therapy, addresses previous concerns about the treatment, and discusses focal therapy failure and how to address it. Focal therapy is best used in intermediate-risk patients with localized lesions and should be conducted using MRI-guided biopsy. Dr. Marks identifies four reasons why focal therapy may fail: 1) heat sink effect from blood vessels surrounding the prostate; 2) field effect in which there is progression of low-risk cancer; 3) staging effect in which inaccurate localization leads to missing cancer cells; and 4) margin effect in which the satellite cancer area is missed. In the latter, MRI typically underestimates both tumor volume and tumor geometry. To address this, Dr. Marks describes a method to determine the tumor margins and create a customized treatment area by using biopsy cores and MRI. For a high-intensity focused therapy (HIFU) plan, the MRI visible treatment margin is used as a base and a paraboloid shape is then overlaid on the image. Then, the positive and negative biopsy site locations are overlaid and used as a guide to contract or expand the area. This process allows clinicians to spare the maximum amount of prostate tissue while not missing cancer cells. He emphasizes that doctors must take extra care to avoid the urethra when using HIFU. Dr. Marks then discusses hemi-gland ablation using HIFU and cryoablation. He concludes by highlighting the advantages of focal therapy, noting that it is safer than surgery or radiation, is effective, preserves options for further focal treatment or radical options if needed, and that patients prefer it.

About the Southwest Prostate Cancer Symposium 2020 virtual conference:
Presented by Program Chairs Nelson N. Stone, MD, and Richard G. Stock, MD, this virtual conference educated attendees about advances in the management of localized and advanced prostate cancer, with a focus on imaging, technology, and training in the related devices. It included a scientific session, as well as live demonstrations of surgical techniques. You can learn more about the conference, including the 2021 iteration, here.