BERKELEY, CA (UroToday.com) - Prostate Cancer (PCa) is the most common cancer in the elderly population in Europe, with an incidence rate of 214 cases per 1 000 men, outnumbering lung and colorectal cancer.[1]
Screening based on the use of Prostatic Specific Antigen (PSA) has provided a constant increase in the incidence of the diagnosis of PCa. Despite the novel imaging techniques available in the study of prostatic diseases, the standard for the definitive PCa diagnosis is still represented by Transrectal Ultrasound (TRUS) guided biopsy, so ultrasound imaging of the prostate plays a central role in the diagnosis of PCa. The conventional grey-scale US image of PCa is of a hypoechoic lesion, and while approximately 39% of all cancers are represented by isoechoic areas, up to 1% of lesions may be hyperechoic.
It is known that hypoechoic areas are not pathognomonic for PCa; prostate dysplasia, inflammation, granulomatous prostatitis, fibrosis, prostatic infarct, and lymphoma may all appear as hypoechoic lesions. Indeed, when there is a hypoechoic area, the Positive Predicting Value (PPV) of the TRUS increases if associated with a positive DRE and a high PSA value.
PCa seems to be associated with an increased microvessel density compared with benign prostatic tissue[2] and the assumption that tumor growth relies on the development of additional blood vessels has been pointed out by several recent papers. Early results with color Doppler (CD) US suggest that up to 85% of men with PCa greater than 5 mm in size have visibly increased Doppler flow in the area of tumor involvement.[3] However, as the evaluation of CD ultrasound is based on a subjective estimation by the examiner, the role of CD sonography in improving the detection and targeting of PCa needs to be reassessed.[4]
Literature reported that a 12-core biopsy was not superior in prostate cancer diagnosis compared with 8-core biopsy, underlining that targeting the peripheral zone is more important than the number of biopsy cores.[5] Other studies suggest that grey-scale and Doppler sonography are useful to select biopsy sites in patients with PCa, thus, although normal sonographic findings should not preclude biopsy, region with grey-scale or Doppler abnormality may be preferentially sampled in patients with limited tolerance or at high risk for multiple biopsies.[6] Moreover CD should become also a part of transrectal sonography of the prostate to improve detection and targeting of cancer lesions.
Our experience suggests that hypervascularized areas visualized with an abnormal or increased flow on CD sonography should be more targeted by biopsy. Moreover, CD seems to be useful, in association with random 8-12 cores peripherally biopsies, for increasing the detection rate of PCa, as hypervascular CD sonography areas are often at major risk of PCa.
In our study, we evaluated 144 subjects with an increased PSA value or with a suspicious digital rectal examination (DRE). Grey-scale TRUS was performed with and without a CD US standard sequence, considering CD US positive or negative on the basis of the presence or absence of vascular abnormality. PCa was detected in 71 (49.3%) patients out of the 144. Fifty-eight of the 71 patients had a hypoechoic area at US scan and 27 had a CD abnormality. We obtained 1 537 cores, all in the peripheral zone, 1 440 cores derived from a random cores biopsies, 70 cores from hypoechoic areas visualized at US scan, and 27 from abnormal CD flow areas. Among the 1 440 cores obtained from the random cores biopsy, PCa was found in 246 of them (17.1%). Focusing only on the 70 bioptic cores obtained from the hypoechoic areas, we had a 65.7% detection rate (46 positive cores) and a 22.2% detection rate of targeting-CD abnormal areas.
In conclusion, on the one hand CD sonography seems to be useful in targeting lesions in the transition zone[7] but has little to offer in peripheral zone lesions, on the other it is suggested to be useful for detecting PCa in peripheral prostatic biopsy when used in combination with grey-scale TRUS, in predicting tumor progression or prognosis and to monitor the effects of anti-angiogenic agents.[8] Thus CD US showed to be a complement to grey-scale imaging of prostate, unless a negative CD image should not preclude biopsy and so the role of CD still need to be clarified.
References:
- Boyle P, Ferlay J. Cancer incidence and mortality in Europe 2004. Ann Oncol 2005; 16(3):481-8.
- Bigler SA, Deering RE, Brawer MK. Comparison of microscopic vascularity in benign and malignant prostate tissue. Hum Pathol 1993; 24:220-226.
- Rifkin MD, Sudakoff GS, Alexander AA. Prostate: techniques, results, and potential applications of Color Doppler US scanning. Radiology 1993; 186:509-513
- Alexander M. To color Doppler image the prostate or not: that is the question. Radiology 1995; 195:11-13.
- Abd TT, Goodman M, Hall J, et al. Comparison of 12-Core Versus 8-Core Prostate Biopsy: Multivariate Analysis of Large Series of US Veterans. Urology 2011; 77(3):541-7
- Halpern EJ, Rosenberg M, Gomella LG. Prostate cancer: contrast-enhanced us for detection. Radiology. 2001; 219(1):219-25.
- Shigeno K, Igawa M, Shiina H, et al. The role of Colour Doppler ultrasonography in detecting prostate cancer. BJU Int 2000 ;86:229-233.
- Shigeno K, Igawa M, Shiina H, et al. Transrectal color Doppler ultrasonography for quantifying angiogenesis in prostate cancer. BJU Int 2003; 91:223-226.
Written by:
Alessandro Del Rosso, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
University of L’Aquila, Department of Health Science, Mazzini Hospital, Teramo, Italy
Does transrectal color Doppler ultrasound improve the diagnosis of prostate cancer? - Abstract
