Many prostate tumors are detected at a very early stage when they are small and are confined to one region of the prostate gland. These tumors cannot be felt in a digital rectal exam. They may be slow growing and pose little immediate risk to a patient's life. However, because it can be difficult to predict which tumors will become life threatening, you or your doctor may want to eliminate a clinically localized early-stage tumor rather than pursue active surveillance.
Surgical oncologist Vincent Laudone explains how focal therapies are used to treat very small tumors in the prostate.
Memorial Sloan-Kettering offers men with small, localized prostate tumors a safe and effective treatment approach called focal therapy. Focal therapy is a general term for a variety of noninvasive techniques for destroying small tumors inside the prostate — leaving the gland intact and sparing most of its normal tissue. In appropriate situations, focal therapy can offer several advantages for men with early prostate cancer:
- Focal therapy can effectively destroy specific areas of cancer within the prostate while preserving normal prostate tissue and function.
- Side effects of focal therapy — including changes in urinary and sexual function — are often temporary and may be less severe than those associated with more-aggressive treatments.
- Because focal therapy causes minimal injury to the prostate gland, it does not preclude further treatment with radical prostatectomy, radiation therapy, or additional focal treatment to another part of the gland, if necessary. Cancer that returns after radiation therapy may be treated with focal therapy.
- Focal therapy is often performed on an outpatient basis or with a single overnight hospital stay.
Memorial Sloan-Kettering's Approach to Focal Therapy
Memorial Sloan-Kettering's prostate cancer experts abide by a rigorous set of standards for selecting patients who are most likely to benefit from focal therapies. This includes performing a thorough evaluation to confirm that the tumor is small and localized, and that a more extensive treatment isn’t required to eliminate a larger or more aggressive tumor.
To determine whether focal therapy is right for you, we perform an MRI of the prostate to identify the exact location of the tumor and to rule out any evidence of more-aggressive disease. Our doctors also perform a careful biopsy to complete the initial diagnosis, confirming the location and other features of your tumor. In some cases, we also utilize an advanced MRI technique — developed at Memorial Sloan-Kettering — that fuses MRI scans with ultrasound images to look for cancer in other areas of the prostate. (A second biopsy may also be advised to ensure that the cancer is as limited as it appeared in the first biopsy and that there are no other areas of cancer in the gland.)
Following your treatment with focal therapy, our physicians will carefully monitor your progress. In addition to prostate-specific antigen (PSA) testing and examination, you may need further MRI and ultrasound studies to assess the effects of your treatment. These studies may also serve as a guide for a follow-up biopsy. These follow-up strategies are more accurate than a PSA test alone in determining whether a treatment was effective. If follow-up tests indicate that the cancer has returned, Memorial Sloan-Kettering offers many other treatment options after focal therapy.
Types of Focal Therapy
Memorial Sloan-Kettering offers a variety of focal therapies, including some novel techniques that are only available in our clinical trials. Our doctors can determine whether focal therapy is appropriate for you, and which approach is likely to be most effective. Factors we consider include the size of your prostate, the location and size of your tumor, your PSA level, and other characteristics.
Some focal therapies, called thermal focal therapies, use either heat or cold to destroy tumors. Thermal focal therapies include:
Interstitial Laser Therapy
A thin, flexible laser fiber is placed directly into the tumor, and MRI scans are used to guide the delivery of laser energy to the tumor with pinpoint precision. The laser superheats and destroys small prostate tumors.
In focal cryoablation a needle-thin probe delivers a solution that surrounds the tumor and kills it by freezing it to a very low temperature. Researchers at Memorial Sloan-Kettering are evaluating the effectiveness of this new form of cryoablation that destroys only the tumor while sparing most of the prostate. Preliminary evidence suggests that focal cryoablation may provide an effective alternative to radical prostatectomy for small, localized tumors. Because focal cryoablation targets only a small area within the prostate, it also has fewer side effects than other cryoablation techniques, which freeze the entire prostate gland.
High-Intensity Focused Ultrasound (HIFU)
HIFU uses the energy of sound waves, directed to the tumor with the help of MRI scans, to superheat and eliminate small tumors. HIFU is an attractive focal therapy approach because it is relatively noninvasive. The effectiveness of this treatment is monitored in real time, using MRI to measure the temperature within the prostate during therapy. Memorial Sloan-Kettering offers HIFU focal therapy to selected patients through a clinical trial.
Memorial Sloan-Kettering also offers nonthermal focal therapies, which use other methods to destroy tumors without harming the entire prostate gland. These therapies include:
Irreversible Electroporation (IRE)
This nonthermal ablation technique uses a device called the NanoKnife® to pass an electrical current through the tumor. The electricity creates very tiny openings (called pores) in tumor cells, leading to cell death. Ultrasound or CT is used to focus the current precisely on the tumor, sparing blood vessels and other tissues.
Vascular Targeted Photodynamic Therapy (VTP)
A drug that destroys tumor cells and the blood vessels that support them is given intravenously and moves to the inside of the tumor. The drug is activated by exposing it to light of a very specific color (wavelength), which is delivered to the tumor site with specially designed fibers placed within the prostate. Currently, the drug used in this therapy is only approved for use outside the United States. However, eligible patients can receive VTP through a clinical trial at Memorial Sloan-Kettering.