MRI Can Halve Prostate Cancer Over-Diagnosis

A new study suggests that screening by magnetic resonance imaging (MRI) and targeted biopsies could significantly reduce prostate cancer (PC) over-diagnosis.

Researchers at Karolinska Institutet (Solna, Sweden) and Karolinska University Hospital (Stockholm, Sweden) conducted a population-based study of 12,750 (50 to 74 years of age). Those with prostate-specific antigen (PSA) levels of 3 ng/ml or higher were randomly assigned to undergo standard biopsy or MRI, with targeted biopsy added if MRI results suggested PC. The primary outcome was proportion of men in whom clinically significant PC was diagnosed; a key secondary outcome was the detection of clinically insignificant cancers.

The results showed that 1,532 men had PSA levels of 3 ng/ml or higher; 603 were assigned to the standard biopsy group and 929 to the targeted biopsy group. In intention-to-treat analysis, clinically significant cancer was diagnosed in 21% in the targeted biopsy group, as compared with 18% in the standard biopsy group. The percentage of clinically insignificant cancers was lower in the targeted biopsy group (4%) than in the standard biopsy group (12%). The study was published on July 9, 2021, in The New England Journal of Medicine (NEJM).

“High rates of overdiagnosis are a critical barrier to organized PC screening. Most countries have not introduced nationwide PC screening, as current methods result in over-diagnoses and excessive and unnecessary biopsies,” said lead author urologist Tobias Nordström, PhD, of Karolinska Institutet. “Our results show that modern methods for PC screening maintain the benefits of screening, while decreasing the harms substantially. This addresses the greatest barrier to the introduction of nationwide screening.”

Current PC screening methods, which include prostate-specific antigen (PSA) tests combined with traditional biopsies, often result in unnecessary biopsies, and the detection of numerous minor low-risk tumors. Consequently, no country except Lithuania has chosen to introduce a nationwide PC screening programme, as the benefits do not exceed the disadvantages.

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