By: Dan Sperling, MD

Radical prostatectomy, or surgical prostate removal, is considered the gold standard of prostate cancer treatment. However, failure rates range from 15-40%,[i] meaning that the scalpel did not get all the cancer. In other words, the tumor had already penetrated into and possibly beyond the outer edge (capsule) of the gland. This is called extracapsular extension or ECE (extra = outside). It is sad when a surgeon must tell a patient, “We found that the tumor had penetrated the capsule.” Often, a course of radiation will then be prescribed in hopes of destroying the cancer while it is still in the prostate bed—but the patient must live with the possible aftermath (incontinence, impotence) of the surgery, and with the hindsight that the surgery could have been avoided while other treatments were pursued to begin with.

Until recently, the ways to gauge ECE before treatment were based on a combination of ultrasound imaging plus clinical factors (PSA, Gleason grade, cancer stage.) Certain prominent features that are telltale signs of ECE can be seen on high resolution ultrasound: for example, an irregular bulge in the capsule, asymmetry of the neurovascular bundle, and other abnormalities. However, according to Radiopaedia, “MRI is much more superior than transrectal ultrasound, CT and digital rectal examination in detecting extracapsular spread as well as seminal vesicular invasion in prostate cancer.”[ii]

A team of researchers set about to determine how well 3T multiparametric MRI identifies ECE. They presented an encouraging paper at the 2014 American Urological Association meeting in Orlando, FL. Out of 620 patients at their site who underwent 3T mpMRI, 112 had radical prostatectomy so the analysis of the surgically removed specimens was available. A single reader with expertise in prostate MRI read the pre-treatment images, and his interpretations were then correlated with each patient’s pathology report. Although a single, small focus of ECE was difficult to detect by MRI (later identified by examination of the removed gland) the imaging was highly accurate in locating the size and location of more extensive ECE. The study authors reported that extensive ECE could be identified in all prostate zones, but the apex was most difficult. They concluded, “Lesions reported as suspicious or definite for ECE on MRI predict extensive ECE on pathology.”[iii]

Although late detection of prostate cancer is unfortunate, 3T mpMRI does patients a service by sparing them a surgical procedure that can impair their quality of life, even if only temporarily. Foreknowledge allows them to move quickly to the most effective minimally invasive and medical treatments that can address the nature of their disease—giving the most hope and the best quality of life.