MRI Helps ID Low-Risk Prostate Cancer Patients

Magnetic resonance imaging of the prostate can help identify men who have low-risk prostate cancer, thus likely benefit from active surveillance rather than immediate treatment, say researchers in a study in the October issue of The Journal of Urology.

Concerned that the increasing number of PSA screenings was resulting in a high rate of treating low-risk prostate cancers, researchers from Memorial Sloan-Kettering Cancer Center in New York undertook a study to determine if MRI of the prostate would be feasible for detecting which men would benefit from active surveillance.

The researchers performed endorectal MRIs between initial and confirmatory biopsies on 388 men who had an initial prostate biopsy performed between 1999 and 2010, had a Gleason score of six or less, and had a biopsy to confirm the assessment within six months of initial diagnosis.

Three radiologists, one with about 50 prostate image readings experience, one with approximately 500 readings experience, and one with over 5,000 readings experience, interpreted the results and they each assigned a score of one (definitely no tumor) to five (definitely a tumor) on the findings. Their findings were compared to each other.

Researchers noted that MRI scores of two or less were highly associated with low-risk features on confirmatory biopsy. In 20 percent of the cases (79), Gleason scores were upgraded and patients who were assigned higher MRI scores were more likely to have their disease upgraded upon confirmatory biopsy.

Agreement was strongest between the two most experienced radiologists. “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 a substantial number of patients,” lead investigator Hebert Alberto Vargas, MD, said in a release.

An accompanying editorial by Guillaume Ploussard, MD, PhD, of the CHU Saint-Louis, APHP, Paris, France, noted, “The primary issue is to reduce the number of clinical settings in which the urologist and the patient face the situation of an increased PSA and an uncertain diagnosis. 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 specific zones.”