Shear-wave elastography may improve prostate cancer detection

1. Among men referred for prostate biopsy due to an elevated prostate-specific antigen level or an abnormal digital rectal exam, the use of real-time shear-wave elastography (rtSWE) was associated with a high sensitivity for prostate cancer detection and a low false-negative rate.

Evidence Rating Level: 2 (Good)  

Study Rundown: Prostate cancer is the most common malignancy and the third leading cause of cancer-related mortality in American men. While the widespread use of prostate-specific antigen (PSA) screening has led to a dramatic down-staging of prostate cancer at the time of diagnosis, the current diagnostic standard-of-care is limited by low sensitivity and a high rate of false-positive biopsies. Promising preliminary evidence for improved tumor detection has been obtained with real-time shear-wave elastography (rtSWE), an operator-independent technique that uses ultrasound (US) to assess elasticity and quantify tissue stiffness, which is increased in cancer. In the present study, the performance of rtSWE was prospectively assessed in the diagnostic evaluation of peripheral zone prostate cancer. Among men with high PSA levels and/or abnormal digital rectal examination results, the assessment of prostate stiffness with rtSWE improved prostate cancer detection and was associated with a high sensitivity and with few false negatives, resulting in a high negative predictive value. Results further suggested that the use of rtSWE may allow patients to undergo fewer biopsies, if validated for diagnostic use on a larger scale. The primary limitations of this study were the lack of inter- and intra-observer variability data and the lack of a control group against which the performance of rtSWE could be compared. Future randomized trials are warranted before rtSWE can be confidently incorporated into the management of patients with suspected prostate cancer.

Click to read the study in Radiology

Relevant Reading: Prostate cancer localization with dynamic contrast-enhanced MR imaging and proton MR spectroscopic imaging.

In-Depth [prospective cohort]: One hundred eighty-four consecutive male patients with an elevated PSA (mean value 7.1ug/L) or an abnormal digital rectal exam were prospectively enrolled. Transrectal rtSWE of the prostate was performed in all patients after a conventional transrectal US assessment and before US-guided biopsy (average 11.89 biopsies per patient). Elasticity measurements from rtSWE were matched with the pathologic biopsy results and diagnostic performance of rtSWE was assessed. Using the Youden index, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. An rtSWE elasticity cutoff of 35 kPa was found to reliably differentiate between benign and malignant lesions. Out of the 129 positive biopsy samples (size ≥3 mm; Gleason score ≥6) identified in 68 patients, the sensitivity, specificity, PPV, and NPV of rtSWE were determined to be 96% (95% CI:95-97%), 85% (95% CI:83-87%), 48% (95% CI:46-50%), and 99% (95% CI: 98-100%), respectively. Prostate cancer grades from patients in the study were mainly between Gleason 6 and 7 (106 of 129 cancers, 82.2%). The positive biopsy rate was 12.4% using standard diagnostic methodology, but could have been increased to 47.5% using rtSWE-based biopsies with a resultant 74.4% decrease in the number of biopsies performed.

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