When prostate cancer recurrence after radiation therapy is suspected, clinicians should perform systematic biopsy of the whole prostate in addition to a multiparametric MRI-targeted biopsy to identify all local prostate cancer lesions for salvage focal therapy, according to investigators.
MRI-targeted biopsy frequently misses recurrent lesions in this setting, Taimur T. Shah, MBBS, PhD, of Imperial College London in the UK, and colleagues reported in European Urology. In their prospective study of 144 patients with biochemical failure, 111 men (77%) had cancer recurrence detected on any biopsy. An MRI-targeted biopsy alone would have missed undetected tumors in unsampled prostate quadrants in 59% of patients. MRI-undetected tumors, defined as a Likert scale of 1-2, were typically smaller (4 vs 7 mm maximum cancer core length) and a lower grade group.
Among 84 men who also underwent an MRI-targeted biopsy, 73 (87%) had recurrent cancer diagnosed. Of these, 43 (59%) had biopsy-confirmed localized T3b or lower radiorecurrent cancer suitable for focal ablation, the investigators reported.
If salvage focal ablation is planned, an MRI-targeted biopsy alone is insufficient for prostate mapping. As Dr Shah’s team noted, “Systematic sampling of the whole gland should be considered in addition to an MRI-targeted biopsy to capture both MRI-detected and MRI-undetected disease.”
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The study population consisted of participants in the FOcal RECurrent Assessment and Salvage Treatment (FORECAST; NCT01883128) trial. All patients underwent MRI with 5 mm transperineal template mapping biopsies, and a subset had additional MRI-targeted biopsies. Investigators studied 4 biopsy strategies involving an MRI-targeted biopsy with systematic biopsies of 1-2 other quadrants.
MRI scans with Likert scores of 3 to 5 were deemed suspicious for targeted biopsy. Whether contemporary use of PI-RADS for scoring MRI images would have altered these results requires further research. Prostate-specific membrane antigen (PSMA) PET/CT also may better detect occult recurrences both inside and outside the prostate.
In an accompanying editorial, Amar U. Kishan, MD, of the University of California-Los Angeles, and colleagues noted that these study findings have “clear implications not only for ablative therapies such as high-intensity focused ultrasound but also for other potentially focal treatment strategies, such as re-irradiation.”
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
References
Light A, Kanthabalan A, Otieno M, et al. The role of multiparametric MRI and MRI-targeted biopsy in the diagnosis of radiorecurrent prostate cancer: an analysis from the FORECAST trial. Eur Urol. 2024 Jan;85(1):35-46. doi:10.1016/j.eururo.2023.09.001
Kishan AU, Valle LF, Marks LS. Bullseye or tip of the iceberg: Magnetic resonance imaging-visible disease in radiorecurrent prostate cancer. Eur Urol. 2024 Jan;85(1):47-48. doi:10.1016/j.eururo.2023.09.01835-46