Dr. R. Jeffrey Karnes is an Associate Professor and Vice Chair of the Urology Department at the Mayo Clinic in Rochester, Minnesota.
Prostatepedia spoke with him about salvage focal therapy for recurrent prostate cancer.
What is focal therapy?
Dr. Karnes: Focal therapy is partial treatment of the prostate gland as opposed to whole-gland treatment (i.e., radical prostatectomy, brachytherapy, and photon or proton radiation therapy).
How did focal therapy even become in vogue? To abate some of the potential side effects of whole-gland treatment. It is exciting and promising, yet remains investigational.
Isn’t a focal approach common in other kinds of cancers?
Dr. Karnes: It can be. The most common is probably breast cancer. I’m far from an expert in breast cancer, but recurrence rates can be higher with focal therapy, meaning a lumpectomy or quadrantectomy, where a quadrant of the breast is removed. But, the survival has been similar between partial- vs. whole-breast treatment.
Why not the prostate? I would say that focal therapy, in general, hasn’t risen to the forefront in the United States or internationally. There are a couple of limitations for focal therapy in general:
1) What do we know about prostate imaging? Prostate cancer is known to be a multifocal cancer within the prostate. The multiparametric MRI is good. It’s not perfect. But even if we can identify a small focus of intermediate-grade prostate cancer, are we certain that is truly the disease to treat, as opposed to some scattered higher-grade cancer that may not be showing up on MRI, but hopefully might get picked up on a whole-gland biopsy done along with a targeted biopsy? I think we’re getting to the point where an MRI is pretty good at imaging the entire prostate.
2) We still have a second unresolved issue of what constitutes the biological index lesion of the cancer. If we do have multifocality, are we sure exactly which focus to treat? Even some of the well-known researchers in focal therapy (focal cryotherapy, high-intensity focused ultrasound [HIFU]) can still have patients with a fairly high recurrence, or persistence of the cancer after the partial or focal therapy about 20% of the time.
What is salvage focal therapy?
Dr. Karnes: Focal salvage therapy is focal therapy done when a man recurs after primary treatment. There is more at risk with focal salvage therapy. What do I mean by more at risk? Obviously, salvage therapy means that there has already been a primary treatment that has failed, so there is even more impetus to get it right the second time around. For that second time around, if we go back to those two items that I mentioned above (imaging and the biology of the index lesion), there has not been, to my mind, enough research into MRI imaging of recurrent prostate cancer. More research needs to be done into the MRI performance accuracy after a radiation.