Is pelvic MRI imaging sufficient cross-sectional imaging for staging intermediate and high-risk prostate cancer?

The American Urological Association's (AUA) and National Comprehensive Cancer Network's (NCCN) provide highly recognized guidelines for staging prostate cancer (CaP). However, both are vague as to specific type of cross-sectional imaging (CT vs. MRI) and extent (abdominal vs. pelvis), thereby raising concern for overlapping imaging. We investigated if current AUA and NCCN CaP staging guidelines can become more specific yet maintain sufficient staging.

We identified 493 patients diagnosed with CaP between 2011 and 2017 and focused analysis on those with AUA and NCCN Intermediate risk (IR) and High risk (HR) groups. Type of staging imaging was recorded and frequency of overlapping (CT + MRI) and abdominal imaging determined. Significance of radiologist findings, for both overlapping and abdominal imaging, were classified as nonurologic, nonsignificant urologic, and CaP significant.

Among IR and HR AUA and NCCN risk groups, 82 (35.7%) and 95 (37.3%) patients, respectively, experienced overlapping imaging, of which only 7 patients in AUA and 9 patients in NCCN risk groups had an abnormal CT with normal MRI. However, only 3 of these CTs had CaP significant findings, of which 2 identified bone metastases, which were subsequently detected on bone scan. In regard to the extent of imaging, a total of 157 (68.2%) AUA and 178 (69.8%) NCCN IR and HR patients received abdominal scans, of which only 46 (20.0%) and 49 (19.2%) were abnormal among AUA and NCCN risk groups, respectively. Among these abnormal abdominal scans, only 10 showed CaP significant findings, of which half were suspected bone metastases, and confirmed on recommended bone scan.

Due to nonspecific staging guidelines in IR and HR CaP regarding type and extent of cross-sectional imaging, patients are frequently receiving imaging of overlapping locations. Based on low occurrences of unique CaP significant findings on CT and abdominal imaging, our exploratory analysis suggests that narrowing cross-sectional imaging recommendations to pelvic MRI may reduce imaging overlap while maintaining sufficient staging.