MRI Scans May Improve PCa Recurrence at Low PSA Levels

Dynamic contrast enhanced (DCE) endorectal magnetic resonance imaging (MRI) of the pelvis may offer an effective method of assessing for local recurrence of prostate cancer (PCa) after prostatectomy, according to Texas researchers.

The approach was able to detect local recurrences in men with PSA values as low as 0.3 ng/mL.

These findings suggest that it may be possible to use this type of MRI scanning to allow for higher radiation treatment dosages and subsequently achieve higher cure rates.

“Being able to identify such patients is beneficial, as it would be predictive of response to salvage radiation therapy,” said lead investigator Seungtaek Choi, MD, of M.D. Anderson Cancer Center in Houston. “It also may allow a radiation oncologist to treat the area of recurrent cancer to a higher radiation dose.”

Dr. Choi and his colleagues evaluated 389 post-prostatectomy patients treated between January 2004 and October 2010, with 143 patients receiving a DCE endorectal MRI to determine if cancer cells were still present in the area of the surgical bed. The imaging technique identified 35 patients with suspicious MRI findings suggesting local recurrence. A total of 26 patients were then biopsied, with 23 of the 26 showing cancer. About one third of patients with a biopsy-proven recurrence after suspicious MRI finding had a PSA of less than 1, with several having a PSA as low as 0.3.

A scan of the surgical bed is typically performed after a prostatectomy and before salvage radiation therapy in patients with a rising PSA. An MRI scan can differentiate between soft tissues better than a traditional CT. The low PSA levels at which the MRI could determine recurrent disease was surprising, according to Dr. Choi, who presented the study findings at the Cancer Imaging and Radiation Therapy Symposium in Atlanta.

Nine patients had prostate/seminal vesicle fossa biopsies performed even though they did not have any suspicious findings on the MRI. Of these patients, only one had a pathologically proven local recurrence. The negative predictive value of DCE endorectal MRI was 88.9%.