Magnetic resonance imaging (MRI) of the prostate prior to initiation of active surveillance (AS) for prostate cancer decreases the cumulative probability of discontinuing AS at 2 years, according to investigators.

MRI of the prostate after starting AS, however, increases the cumulative probability of discontinuing AS compared with not performing MRI.

Henk B. Luiting, MD, of Erasmus University Medical Centre Cancer Institute in Rotterdam, The Netherlands, and colleagues analyzed data from men who participated in the prospective Prostate Cancer Research International Active Surveillance (PRIAS) study. Investigators divided patients into 3 subpopulations: patients diagnosed before 2009 without MRI before or during AS (group A, 500 patients); patients diagnosed without MRI but who underwent MRI within 6 months after diagnosis (group B, 351 patients); and patients who underwent MRI before diagnosis and during follow-up (group C, 435 patients).

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In group A, the cumulative probability of discontinuing AS at 2 years was 27.5%, with prostate cancer Grade Group reclassification solely accounting for 6.9% of the discontinuation. The proportions for group B were 30.9% and 22.8%, respectively, and 24.2% and 13.4%, respectively, for group C.

“These results suggest that the use of MRI could lead to more patients being considered unsuitable for AS,” Dr Luiting and colleagues concluded in a paper published in Prostate Cancer and Prostatic Diseases. “Considering the excellent long-term cancer-specific survival of AS before the MRI era, the increased diagnostic accuracy of MRI could potentially lead to more overtreatment if definitions and treatment options of significant PCa are not adapted.”

The majority of patients in the 3 groups had stage T1c cancer: 82.6%, 89.7%, and 88.5% for groups A, B, and C, respectively. All patients in groups A and B and 84.6% of those in group C had Grade Group 1 disease. In all groups, patients had a median age of 65 years at diagnosis.


Luiting HB, Remmers S, Valdagni R, et al. What is the effect of MRI with targeted biopsies on the rate of patients discontinuing active surveillance? A reflection of the use of MRI in the PRIAS study. Published online April 8, 2021. Prostate Cancer Prostatic Dis. doi:10.1038/s41391-021-00343-2