MRI Scans Could Predict Postradiation Urinary Side Effects in Patients With Prostate Cancer

Get Permission

Researchers have discovered that patients with longer prostatic urethras may have an increased risk of experiencing moderate and chronic urinary side effects after receiving radiation for prostate cancer, according to a recent study published by Lee et al in Academic Radiology. The new findings suggested that a simple magnetic resonance imaging (MRI) scan and a new metric may be effective at determining urethra length.


To date, researchers have struggled to determine the risk factors that could shed light on which patients might experience postradiation urinary side effects.

Although radiation—one of the most common treatments for prostate cancer—is considered safe and well tolerated for most patients, those who experience more side effects may experience a reduced quality of life. 

Study Methods and Results

In the new study, the researchers enrolled 361 patients with prostate cancer and asked them to undergo MRI scans following radiation.

The researchers found that every 1-cm increase in length of the prostatic urethra shown on the MRI scans increased the risk of experiencing urinary side effects—such as having the urgency to urinate and needing to urinate more often—by about 60%. The patients whose prostatic urethra lengths were greater than 4.6 cm were nearly twice as likely to develop these symptoms.  

“We believe this particular area is more exposed to the radiation doses patients receive, resulting in direct inflammation,” explained senior study author Kiran Nandalur, MD, a radiologist at Corewell Health. “While chronic moderate urinary side effects were more problematic in approximately 28% of [patients] after 3 years, the good news is less than 3% of [them] experienced severe urinary side effects,” he added. 

The researchers noted that there are currently very few known risk factors for those who will experience side effects after radiation and reported that details such as the type of radiation or underlying medical conditions were not predictive of symptoms—underscoring the difficulty of previously assessing risk factors in this patient population. The researchers highlighted the need for novel and innovative strategies to identify which patients may experience urinary side effects, including the use of MRI technology in prostate cancer care. 


“Our novel MRI metric may help patients know beforehand what their risk is in developing these symptoms and help them make better and more informed decisions on a course of treatment that optimizes quality of life. [Physicians] also can look at ways to better spare the prostatic urethra area from radiation and potentially decrease the side effects,” Dr. Nandalur proposed. “I highly recommend patients talk with their urologists or radiation oncologists about getting a prostate MRI before therapy. It is robust in diagnosing and evaluating the extent of prostate cancer and can potentially help patients maintain a better quality of life after undergoing treatment,” he concluded.

Disclosure: For full disclosures of the study authors, visit

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.