I’m excited to report the recent publication of a clinical trial investigating how MRI-guided biopsies can improve treatment success for prostate cancer (PCa) patients undergoing radiation therapy. “Match the treatment to the disease” is a governing principle in treating PCa. If treatment is too aggressive for insignificant disease, the cancer may be gone but at the price of the patient’s urinary, sexual or bowel function. On the other hand, if significant cancer isn’t treated powerfully enough, the patient pays the price of having it come back (recurrence).

This is where multiparametric MRI (mpMRI) comes into play. By visually revealing the location and characteristics of a suspicious PCa tumor in the prostate, it enables accurate targeting for two key elements of treatment success:

1. Live, real-time mpMRI allows precision aiming of a minimum number of biopsy needles into the core of the suspicious area. This is where the most aggressive cells in a tumor are likely to be, so the pathology report (analysis of needle samples) can guide treatment planning and decisions.
2. Then, based on the images and the pathology report, a doctor knows where and how to direct the most powerful and accurate punch, matched to the degree of PCa aggression.

“Targeting” radiation

By its nature, radiation tends to scatter when it encounters tissue, making it difficult to aim without risk to surrounding tissue. Many improvements have made radiating PCa tumors more controlled. Technologies like Intensity Modulated Radiation Therapy (IMRT) and Stereotactic Body Radiation Therapy (SBRT) allow a much more tailored approach to each patient’s disease, both in location (minimize scatter) and dose (strength of the punch).

The newly published clinical trial I mentioned at the beginning compared the outcomes of radiation treatment between two groups of patients with localized PCa.^[i] There were 102 patients in the study, and all had MRI before treatment. The two groups were as follows: Group A (57 patients) had both an MRI guided biopsy as well as a randomized systematic biopsy; Group B (45 patients) had systematic biopsy alone. All patients were to be treated with radiation. In both groups, many were diagnosed with intermediate-to-higher risk PCa. Thus, the strength and targeting of the radiation had to be customized to the specific tumor location for best possible treatment outcomes.

The average follow-up time was nearly 5 years (57.2 months). They were tracked for what is called biochemical recurrence (BCR), meaning a rising PSA after treatment that signals the PCa is possibly back. What do you think the researchers found?

As the authors report:

• Non-MRI-guided biopsy group – 4 cases of BCR recurrence
• MRI-guided biopsy group – 0 cases of BCR recurrence.

According to the authors, “The MRI-guided biopsy group demonstrated superior BCR-free survival across both intermediate- and higher-risk groups. MRI-guided biopsy was associated with a reduced risk of BCR following definitive EBRT, particularly in intermediate-risk patients. In contrast, systematic random biopsies, even when combined with pre-RT MRI, were linked to poorer intermediate oncologic outcomes.”^[ii]

Let’s put it in simpler words. For PCa patients who will be treated with beam radiation, MRI before biopsy gives important information about the presence and location of a tumor, plus visual clues as to its aggressiveness. While this may assist with the doctor knowing where to concentrate radiation dose, some key information is missing.

A systematic biopsy alone provides cells for tissue analysis, but since systematic biopsies are hit-or-miss when it comes to sampling the most dangerous cells, it’s possible to under-diagnose the true nature of the tumor. Therefore, some patients may be under-treated with a radiation dose inadequate to kill the hardier aggressive cells.

On the other hand, when an MRI-guided targeted biopsy extracts cells from the core of the tumor, it is highly accurate for sampling those cells with more dangerous characteristics. The radiation, then, is calibrated to destroy those cells as well as the less aggressive ones. When this approach succeeds, the probability of BCR is greatly decreased.

The last thing I want to point out is the difference between real-time MRI targeting, fusion-guided targeting, and micro-ultrasound-guided targeting. Although the latter two are used by urologists because the biopsy can be done in the urology suite, there is no substitute for the proven precision of a biopsy done inside the magnet (MRI machine) in a radiology suite. For various reasons, the other two types of “targeted” biopsy generally require additional systematic sampling on top of the targeted biopsy, because real-time MRI is not involved so the visual accuracy is lesser.

I highly recommend that patients with localized PCa who are considering having beam radiation, including proton beam, undergo a real-time, in-bore MRI-guided targeted biopsy. Many times, radiation can’t be repeated if PCa comes back. If you only get one chance at a successful radiation treatment, make it count by getting the best diagnostic information for optimum treatment planning.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

References

[i] Mahamongkol, K., Teyateeti, A., Woranisarakul, V. et al. MRI-guided biopsy reduces biochemical recurrence in prostate cancer patients undergoing radiation therapy: a single-center study from Thailand. Sci Rep 15, 10869 (2025). https://www.nature.com/articles/
[ii] Ibid.