Prostate cancer size is frequently underestimated on imaging

Newly published data recently revealed just how frequently the extent of prostate cancer is underestimated based on imaging measurements. 

The new Insights into Imaging paper details the cases of 202 men with clinically localized prostate cancer and how their pre-operative imaging measurements compared to their post-operative prostatectomy findings. The research team combined measurements derived from patients' multiparametric MRI (mpMRI) exams and ultrasound shear wave elastography (USWE) imaging with their histopathology to create imaging-based, patient-specific whole-mount molds. The 3D-printed slides were used as life-size slice replicas of the patients’ prostate so that experts could observe them in the same size and orientation as was visualized on imaging. 

Through this, the team found that a significant number of men had the size of their prostate cancer underestimated on imaging—82.1% on mpMRI and 64.6% on USWE. This figure could be construed as concerning due to what tumor measurements mean for patients’ disease treatment and/or management, the authors noted 

“The size of cancers seen on imaging is not only used for staging but also for risk stratification, particularly in localized prostate cancer,” corresponding author of the paper Ghulam Nabi, with the Division of Imaging Sciences and Technology at the University of Dundee in the United Kingdom, and co-authors explained. “Mathematical modeling and survival data in other sites show cancers displaying a direct correlation between the size of cancer and its lethality, irrespective of the methods of detection.” 

In this analysis, tumor size was underestimated by a median 7 mm on mpMRI and 1 mm on USWE. Out of the 327 cancerous lesions included, the majority were underestimated by both modalities, but mpMRI showed an approximately 20% higher rate of smaller measurements compared to USWE; this finding was most pronounced on imaging of the mid and apical level of the prostate gland. Clinically nonsignificant cancers were more often underestimated than those deemed clinically significant. 

The findings pertaining to USWE could be of particular importance, the authors suggested. 

“USWE size estimation performed better; however, this modality is not commonly used in clinical practice. In view of this, findings from this study become important for future research in USWE and healthcare practice,” the group indicated. 

The study abstract is available here.