Magnetic resonance-guided focused ultrasound surgery (MRgFUS) uses focused ultrasound energy to heat and destroy a targeted area of tissue, with MRI images guiding treatment. This tissue destruction is called ablation. In prostate cancer, focal treatment targets part of the prostate rather than the whole gland. MRI-guided ultrasound also includes a different technique, transurethral ultrasound ablation (TULSA); its whole-gland treatment results should not be treated as results for focal MRgFUS.

For prostate cancer, MRgFUS has mainly been studied in men whose cancer is confined to the prostate and classified as low or intermediate risk. The aim of focal treatment is to treat cancer while preserving tissue and function. MRI-guided ultrasound has also been studied in smaller groups with higher-risk cancer or cancer returning after radiotherapy. Treatment after radiotherapy has a different risk profile from first treatment. Removal of the prostate is an alternative discussed in this research, but comparisons with earlier surgical patient groups do not establish that MRgFUS is the better choice for an individual. Another cancer-related use of MRgFUS is pain relief for cancer that has spread to bone; pain relief and control of a prostate tumour are different treatment goals.

In men treated with focal MRgFUS for localized prostate cancer, research describes strong cancer control within the treated area, while tissue samples taken elsewhere in the prostate can still reveal cancer. The prostate evidence reviewed in 2026 consists mainly of studies without a comparison group, with short follow-up and differing treatment designs. A 2024 report described treatment of one patient with a recurrent tenosynovial giant cell tumour in the forefoot: the procedure was judged successful and no immediate complications were observed. That immediate result in one patient does not establish lasting tumour control or predict results for other cancers.

In prostate cancer research covering both MRgFUS and TULSA, side effects were mostly mild and temporary, while serious complications were concentrated in treatment for cancer returning after radiotherapy. Cancer outside the area treated with focal MRgFUS is an important concern when there is more than one cancer focus in the prostate. Preserving urinary control and erections is an aim of tissue-preserving treatment, not a guarantee for each patient.

After focal prostate treatment, follow-up research has used systematic biopsies, which take tissue samples from different parts of the prostate. These checks have detected cancer outside the treated area even when control within that area was strong. Follow-up therefore concerns the rest of the prostate as well as the treated target.