MRI identifies PCa active surveillance candidates

October 3, 2012

Adding endorectal magnetic resonance imaging to the initial clinical evaluation of men with clinically low prostate cancer risk helps assess these patients' eligibility for active surveillance, according to a recent study.

Adding endorectal magnetic resonance imaging to the initial clinical evaluation of men with clinically low prostate cancer risk helps assess these patients’ eligibility for active surveillance, according to a recent study.

Researchers from Memorial Sloan-Kettering Cancer Center, New York evaluated 388 patients who had an initial prostate biopsy performed between 1999 and 2010, had a Gleason score of 6 or less, and had a biopsy to confirm the assessment within 6 months of initial diagnosis. An endorectal MRI was performed in all patients between the initial and confirmatory biopsies.

MRI studies were interpreted by three radiologists with different levels of experience. One was a fellowship-trained radiologist who had read approximately 50 prostate MRI examinations before the study (reader 1). The second was a fellow with dedicated training in prostate imaging who had read approximately 500 prostate MRI examinations (reader 2). The third was a fellowship-trained radiologist who had interpreted more than 5,000 prostate MRI examinations (reader 3).

They each assigned a score of 1 to 5 for the presence of tumor on MRI, with 1 being definitely no tumor and 5 being definitely tumor.

On confirmatory biopsy, Gleason scores were upgraded in 79 cases (20%). Patients with higher MRI scores were more likely to have disease upgraded on confirmatory biopsy. An MRI score of 2 or less was highly associated with low-risk features on confirmatory biopsy. Agreement on MRI scores was substantial between readers 2 and 3, but only fair between reader 1 and readers 2 and 3.

"These results suggest that MRI of the prostate, if read by radiologists with appropriate training and experience, could help determine active surveillance eligibility and obviate the need for confirmatory biopsy in substantial numbers of patients," said lead investigator Hebert Alberto Vargas, MD, whose group’s results were published online in the Journal of Urology (Sept. 26, 2012).

In an online editorial in the same issue of the journal, Guillaume Ploussard, MD, PhD, of the CHU Saint-Louis, APHP, Paris, noted, "MRI might help to limit the risk of biopsy under grading. In cases of normal signal in the whole gland, the patient might be reassured and re-biopsy delayed. In cases of a suspicious nodule, re-biopsy would be better justified, and biopsy cores could target suspicious zones."

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