medwireNews: Men with an initial negative transrectal ultrasound (TRUS)-guided biopsy have a higher risk for mortality from causes other than prostate cancer, say investigators who question the need for further diagnostic evaluation in such men, especially if they also have low prostate-specific antigen (PSA) levels.
“[R]estricting these additional investigations to men with high PSA concentrations and other risk factors might lower the risk of overdiagnosis and the number of unnecessary biopsies,” they write in The Lancet Oncology.
But the study authors admit that “[t]he optimum follow-up strategies in men who present with benign initial biopsy results is still unclear, and warrants further investigations, including use of imaging modalities and biomarkers.”
They analyzed data from the Danish Prostate Cancer Registry on 63,454 men referred for a TRUS-biopsy over a 17-year period, during which 43% tested negative on their initial biopsy, 55% were diagnosed with prostate cancer, and the remaining 2% were excluded as their diagnoses were not related to the prostate.
Among men with an initial benign biopsy, the estimated cumulative incidence of prostate cancer-specific mortality at 20 years was 5.2%, compared with 59.9% for mortality from other causes.
By contrast, the cumulative incidence of prostate cancer-specific mortality and mortality from other causes were similar for those with a prostate cancer diagnosis, with estimated 20-year rates of 43.6% and 42.1%, respectively.
PSA levels add to the prognostic value of the initial biopsy, say Nina Klemann (Copenhagen University Hospital, Denmark) and colleagues, although they urge caution in the interpretation of these results since PSA data at diagnosis were available for only 22% of men with a negative result.
Specifically, the 15-year cumulative incidence of prostate cancer-specific mortality in men with an initial benign biopsy was 0.7% for men with PSA levels no higher than 10 μg/L, rising to 3.6% and 17.6% for those with PSA concentrations of 10–20 μg/L and over 20 μg/L, respectively.
Noting that the diagnostic efficiency of TRUS-biopsies has recently been called into question, the authors highlight the PROMIS trial, which showed that multiparametric magnetic resonance imaging (MRI) had a higher sensitivity for identifying clinically significant disease than TRUS-biopsy.
They point out that “the prognostic value of clinically significant prostate cancer detected by MRI-guided biopsy is unknown,” but add: “Nonetheless, MRI, other imaging modalities, or biomarkers could potentially help to reduce the number of men who undergo unnecessary biopsies, especially if these instruments can select men who can avoid any biopsies.”
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