Imaging Prostate Cancer
Posted: Nov 01, 2018
POSTED: November 06, 2017
Dr. Behfar Ehdaie is a urologist at Memorial Sloan Kettering Cancer Center in New York City.
Prostatepedia spoke with him recently about focal therapy and laser ablation.
Dr. Behfar Ehdaie: I initially was exposed to medicine in dealing with some of the medical challenges that my mother faced related to cancer. It made a very large impression on me to see how my mother interacted with her physicians and how she was comforted by so many of them. To be able to give back and to provide comfort to other people with regard to different diseases was very important in my decision to be a doctor.
On top of that, being an effective and good physician were challenges that I found to be stimulating.
Dr. Ehdaie: I think we’ve come to a point in prostate cancer management and treatment in which these distinctions and terminology are becoming more important. As you know, over the past three decades, we have developed proven effective whole-gland treatments for the prostate that include radical surgery and radiation therapy. A less invasive form of prostate cancer treatment must involve less than total treatment of the whole gland. Therefore, the term partial gland has evolved. We use the word ablation to suggest that an area of the prostate will be treated, whether that’s through heating or freezing or other mechanisms to cause cell death and necrosis.
The term focal therapy adds a second dimension to partial-gland ablation. This is a general term to refer to any treatment that offers less than whole-gland treatment for prostate cancer. Focal therapy specifically focuses on an image-guided treatment approach, meaning an area that is visualized is specifically targeted and treated. In partial-gland ablation, we use our current abilities to map the prostate to determine which region is most likely to be involved with cancer; we not only seek to treat that area but also to achieve a margin that may not be visualized on imaging. Focal therapy adds the dimension of image guidance to the armament of prostate cancer treatment, which is more relevant now given that our approach to diagnosing prostate cancer has also evolved over the past decade. We have moved from systematic biopsies to adding biopsies in which we target areas that are first visualized using advanced imaging like multiparametric MRI.
Dr. Ehdaie: In our different studies and trials, we have different forms of treatment. Specifically, in studies in which we define the area of treatment by MRI, we term those treatments focal therapy. We currently have a clinical trial looking at MR-guided high-intensity focused ultrasound (HIFU) that we perform in the MRI suite. We also have two other clinical trials in which we direct our treatment to a region predominantly defined by the biopsy criteria, in which the imaging is an addition to the tools we have used to define where we want to treat. We currently are performing both focal therapy and partial-gland ablation on patients based on the modalities that they would be eligible for.
Dr. Ehdaie: I think ultimately we can make the distinction between patients who need radical surgery or radiation treatment and those patients who need less invasive forms of treatment that we would term partial-gland ablation specifically, without making the distinction with focal therapy to answer this question.
Currently, I believe eligible patients are those who have an intermediate risk prostate cancer defined as Gleason grade 3+4, or in some cases very low-volume Gleason 4+3 prostate cancer defined by prostate needle biopsy and confirmed with a secondary imaging test to rule out other areas of intermediate-risk prostate cancer. Those patients may have other areas of low-grade, low-risk prostate cancer, specifically Gleason 3+3, which would go untreated and be monitored as they currently are in many active surveillance cohorts. I do not believe focal therapy or partial-gland ablation in its current form should be evaluated or used in patients with high-risk prostate cancer; that includes men with Gleason 4+4 or higher, high-volume Gleason 4+3, with imaging characteristics suggesting bilateral intermediate or high-risk disease, or disease that has escaped the prostate, including locally advanced prostate cancer or prostate cancer that has metastasized to the lymph nodes or the bone.