Here in the USA there has been a nucleus of physicians who have argued for years that the use of color Doppler ultrasound enhances the ability to identify and biopsy prostate cancer. New data from Germany are relevant to this conversation.
Mitterberger et al. have just reported comparative (albeit retrospectively analyzed) data on the effectiveness of biopsies guided by transrectal, contrast-enhanced, color Doppler ultrasound (CECD-US) as compared to a systematic biopsy in 1,776 men between 2002 and 2006.
All men who were biopsied had a PSA level ≥ 1.25 ng/ml. Each patient first received just five CECD-US targeted biopsies in hypervascular areas in the peripheral zone of the prostate while receiving a special contrast agent. Subsequently, a second physician took a series of 10 systematically planned biopsy cores (presumably also under ultrasound guidance, although the paper’s abstract does not actually state this).
The results of this retrospective analysis show that:
- Prostate cancer was detected in 559/1,776 patients (31 percent) in total.
- The 5-core CECD-US-guided biopsy identified prostate cancer in 476/1,776 patients (27 percent).
- The 10-core systematic biopsy identified prostate cancer in 410/1,776 patients (23 percent).
- The prostate cancer detection rate using CECD-US targeted biopsy was 10.8 percent (i.e., 961/8,880 cores were positive for cancer).
- The prostate cancer detection rate using systematic biopsy was 5.1 percent (i.e., 910/17,760 cores).
- A positive biopsy for prostate cancer using CECD-US-guided biopsy that was negative using systematic biopsy occurred in 149/559 patients (27 percent).
- A positive biopsy for prostate cancer using systematic biopsy that was negative using CECD-US-guided biopsy occurred in 83/559 patients (15 percent).
What can we make of these data?
Well the authors, to their credit, conclude only that, “This study represents the largest clinical trial to date, demonstrating a [statistically] significant benefit of CECD-US targeted biopsy relative to [systematic biopsy].”
In the favor of CECD-US-guided biopsy, it has to be said that this clearly identified a high number of tumors that were not samples by systematic biopsy — but what we don’t know is what proportion of those 149 tumors might have been identifed with a standard TRUS-guided biopsy using a “black and white” ultrasound system.
The immediate problem would seem to be that color Doppler ultrasound missed 15 percent of the cancers found on a systematic biopsy. That looks like a disturbingly high failure rate for a technology that some people have argued is far better than standard transrectal ultrasound-guided biopsy using standard (“black and white”) ultrasound technology.
Of course what is really needed here is a strict, prospective study of the use of transrectal color Doppler ultrasound-guided biopsy plus (say) an 8-core or 10-core systematic biopsy vs. the same technique using standard TRUS. It will almost certainly never happen. In the meantime, what seems to be the case is that any biopsy today should comprise two elements — a series of systematic biopsies designed to sample specific areas of the prostate (specifically including the apical area) combined with additional biopsy cores from areas that look suspicious under ultrasound guidance. Whether color Doppler ultrasound really enhances the ability to better identify areas that actually turn out to be positive for prostate cancer compared to standard TRUS guidance would appear to still be an arguable point.