Prostate cancer is one of the most frequently diagnosed cancers in men. Traditional approaches like radical prostatectomy and whole-gland radiation therapy offer high rates of cancer control but often carry a substantial risk of side effects impacting quality of life. These whole-gland treatments destroy the entire prostate gland, potentially damaging surrounding nerves and muscles. The development of highly targeted methods provides a middle ground between aggressive treatment and active surveillance, focusing on preserving normal urinary and sexual function while achieving cancer control.
Defining Focal Therapy
Focal therapy is a specialized treatment that precisely targets only the known cancer cells within the prostate, shifting away from treating the entire gland. This technique uses various energy sources to destroy, or ablate, the cancerous lesion(s) while sparing surrounding healthy tissue. The goal is to achieve cancer control in the targeted area with significantly reduced collateral damage to nearby structures. By localizing the destruction, focal therapy aims to minimize side effects like erectile dysfunction and urinary incontinence, providing an active, organ-preserving intervention for localized disease.
Techniques Used in Focal Therapy
Several different energy modalities are employed to physically destroy the targeted tumor tissue in focal therapy.
High-Intensity Focused Ultrasound (HIFU)
One common method is High-Intensity Focused Ultrasound, or HIFU, which uses high-frequency sound waves generated by a probe placed in the rectum. These sound waves are focused precisely on the cancerous area, rapidly heating the tissue to over 60 degrees Celsius, which causes immediate cell death through thermal ablation. The non-invasive nature of HIFU means no incisions are required, and the procedure is often completed in a single session.
Cryotherapy (Cryoablation)
Another established technique is cryotherapy, also known as cryoablation, which destroys tissue by freezing it. Specialized needles or probes are inserted into the prostate to deliver extremely cold gases, such as argon, to the tumor site. This rapid drop in temperature forms ice balls that rupture the cancer cells. Cryotherapy is often guided by ultrasound imaging to ensure the freezing zone is confined to the targeted lesion.
Other Modalities
A third method is Laser Interstitial Thermal Therapy (LITT), also referred to as Focal Laser Ablation (FLA). This technique involves inserting a thin laser fiber directly into the tumor under real-time image guidance. The laser emits high-energy light that heats the targeted tissue, causing thermal coagulation and destruction of the cancer cells. Other emerging modalities include irreversible electroporation (IRE) and photodynamic therapy (PDT), which use electrical pulses or light-activated drugs, respectively, to induce cell death.
Candidate Selection and Criteria
Focal therapy requires careful patient selection, as it is not appropriate for all prostate cancer diagnoses. Ideal candidates have localized, low- to intermediate-risk disease that is clearly visible on advanced imaging. The cancer must be confined to the prostate gland without spread to the seminal vesicles or outside the capsule. Patients with a dominant tumor on one side of the prostate (unifocal or unilateral disease) are considered the most favorable candidates.
Accurate tumor mapping is accomplished through multi-parametric Magnetic Resonance Imaging (mpMRI), which provides high-resolution detail. This imaging is followed by a targeted biopsy to confirm the location and grade of the cancer. The tumor should be Grade Group 2 or 3 (Gleason Score of 3+4 or 4+3). The lesion must be small enough to be treated with an adequate safety margin. Location is also considered, as lesions too close to the urethra or sphincter may risk damage if treated by certain energy sources.
Outcomes and Potential Side Effects
A primary benefit of focal therapy is the improved functional outcomes related to quality of life compared to whole-gland treatments. The procedure spares the neurovascular bundles responsible for erectile function and the muscles responsible for continence, resulting in much lower rates of severe side effects. Studies on focal HIFU show that 98% of patients maintain full urinary continence (pad-free), and a large majority retain erectile function sufficient for intercourse.
The improved functional outcomes necessitate rigorous, ongoing surveillance after treatment. Patients require regular follow-up using Prostate-Specific Antigen (PSA) blood tests, mpMRIs, and repeat biopsies to monitor for recurrence in the treated area and the rest of the gland. Some patients experience treatment failure, with recurrence rates ranging from 25% to 30% over a seven-year period. If the cancer returns or progresses, patients may undergo a repeat focal procedure or transition to a whole-gland treatment like surgery or radiation.