Colour Doppler ultrasonography for detecting perineural invasion (PNI) and the value of PNI in predicting final pathological stage: a prospective study of men with clinically localized prostate cancer

OBJECTIVES

To assess the ability of colour Doppler transrectal ultrasonography (CD-TRUS) to improve the accuracy of detecting perineural invasion (PNI, reported to be an independent predictor of extraprostatic extension) and in predicting the pathological stage of the cancer, comparing it with the results of grey-scale TRUS-guided biopsies.

PATIENTS AND METHODS

This prospective study included 47 men with clinically localized disease; all underwent 10-core TRUS-guided biopsy and two bilateral CD-TRUS-guided biopsies, targeted on the area adjacent to the neurovascular bundle. The rates and accuracy of PNI detection on 10-core and CD-TRUS-targeted biopsies were compared with the pathological outcome. Various patient, clinical and pathological factors were compared, and multivariate analysis used to assess the value of the technique in predicting PNI and pathological outcome.

RESULTS

CD-TRUS-guided biopsies predicted the presence of PNI in the radical prostatectomy specimens with a sensitivity of 89%, and specificity and positive predictive values of 100%. Seven of 24 (29%) patients with PNI on the needle biopsies had pT3 disease. Conversely, the absence of PNI on guided biopsy accurately predicted pathologically localized disease in 96% (negative predictive value) of patients. However, the results of multivariate analysis showed that serum prostate-specific antigen was the only strong predictor of pT3.

CONCLUSION

CD-TRUS is a useful tool for detecting PNI and predicting pathological localized cancer; it can be used in candidates for nerve-sparing radical prostatectomy.