Magnetic resonance imaging findings in prostate cancer patients about to undergo radiation therapy can help predict the likelihood that the cancer will return and spread post-treatment, according to a new study published in Radiology (2008; 247:141-6).

“This is the first study to show that MRI detection and measurement of the spread of prostate cancer outside the capsule of the prostate is an important factor in determining outcome for men scheduled to undergo radiation therapy,” said study co-author Fergus V. Coakley, MD, of the University of California, San Francisco.

The researchers retrospectively reviewed the MRIs of 80 men with prostate cancer who had undergone MRI of the prostate prior to external beam radiation therapy. Details of tumor characteristics, treatment, and outcome were recorded.

Using a Cox regression analysis, the team determined that the presence and degree of extracapsular extension seen on the pre-treatment MRI was an important predictor of post-treatment recurrence and spread. Specifically, patients with extracapsular extension greater than 5 mm were more likely to experience recurrence and spread of their cancers.

“Patients with substantial extracapsular spread of prostate cancer may wish to discuss options for more aggressive therapy with their treating physicians,” Dr. Coakley said.