We have known for many years that, of men who present with an elevated prostate-specific antigen (PSA), more than 50% should likely not undergo biopsy, as they either have no disease or, if they do, it is clinically insignificant disease that does not benefit from treatment. The objective of mpMRI (and a number of serum and urine tests) is to improve the identification of those men with an elevated PSA and significant lesions who would benefit from biopsy and spare those who would not benefit from having to undergo a biopsy. The use of mpMRI before the first prostate biopsy, together with serum or urine biomarkers, can help to prevent unnecessary biopsy and may improve the detection of clinically significant cancer. Precisely how this is best achieved remains an area of controversy. It is clear that mpMRI alone may miss up to 25% of higher-risk tumors. Therefore, a negative mpMRI alone does not preclude a biopsy, but rather one would require an additional serum or urine biomarker, for instance, or perhaps even PSA density, to suggest that the patient is not harboring clinically significant disease. 

Currently, there are numerous serum- and urine-derived risk assessment tests available that are designed to improve the specificity for the detection of clinically significant disease (eg, Prostate Health Index, 4Kscore, SelectMDx, ExoDx). For those who undergo such testing, including mpMRI, the consensus recommendation for the initial biopsy is to perform both targeted and systematic biopsies. Targeting can be cognitive or can be facilitated by MRI/ultrasound fusion–guided software. In patients on active surveillance, measuring PSA density by MRI or ultrasound, together with a validated biomarker test may also help to prevent unnecessary and less frequent biopsy.

Technologies such as mpMRI appear to allow for better visualization of the lesion for “focal” ablation. There are numerous ablative strategies, but the dominant procedures in the United States are cryoablation and high-intensity focused ultrasound. Appropriate patient selection for focal therapy is an ongoing area of investigation. Thus far, the vast majority of those treated with focal therapy have been low- to intermediate-risk patients, many of whom may be good candidates for surveillance alone. I do not think that focal ablation should be used in those who do not require treatment; rather, I feel that it should be reserved for those subsets of patients with higher-grade (eg, Gleason 3 ⁺ 4 or higher) focal lesions (eg, confined to 1 sextant or 2 continuous sextants in the prostate). Such patients can be identified through a combination of systematic and MRI-directed biopsies, which would carefully map the tumor. MRI-guided focal ablation of native or locally recurrent prostate cancer is becoming a viable treatment alternative, but further research is needed to determine the long-term efficacy of this technique.