A new paper in Urologic Oncology, taken in combination with a media release and a video release from the UCLA Health System, have described a sophisticated method of combining data from magnetic resonance imaging (MRI) of the prostate with a three-dimensional (3D) ultrasound system to optimize outcomes of prostate biopsies. The authors are at pains to point out that one of their key objectives in the development and application of this technique is to increase the likelihood of accurate identification and follow-up of patients who would benefit from active surveillance as opposed to invasive treatment. However, the abstract of the actual paper, along with the media release and a brief video created for media distribution actually deal with slightly different opportunities. Without getting into all the details, we shall try to give you the key points. It can be a little difficult to follow how the study was conducted.
Natarjan et al. actually describe three different opportunities related to the use of highly targeted biopsy techniques in the initial evaluation of men at risk for prostate cancer and subsequent follow-up of men on active surveillance protocols:
- The clinical evaluation of a 3D transrectal ultrasound biopsy tracking and targeting device (Artemis) developed by Eigen in the initial evaluation of men at risk for prostate cancer.
- The targeted re-biopsy of men initially diagnosed with low-risk prostate cancer as part of an active surveillance protocol.
- The combination of data from pre-biopsy MRI scans with the use of the Artemis technology to increase the potential accuracy of diagnosis.
The Artemis equipment was actually approved by the Food & Drug Administration nearly 3 years ago. However, this paper appears to be the first publication to offer a detailed clinical evaluation of the application of this technology.
The study enrolled 218 men who were all scheduled for prostate biopsy. In the first part of the study, all 218 subjects underwent conventional TRUS. Then, 171 men had the Artemis device linked to their ultrasound probe; their prostate was re-scanned; a 3D reconstruction was created; and they were biopsied with their prostate biopsy being visualized in 3D and tracked electronically. The other 47 men all received a multi-parametric 3 Tesla MRI, incorporating T2-weighted images, dynamic contrast enhancement, and diffusion-weighted imaging, in advance of the TRUS, allowing the stored MRI images to be fused with real-time ultrasound during biopsy. Finally, 11/171 men who underwent the 3D TRUS-Artemis biopsy were later re-biopsied to evaluate the ability of the Artemis device to guide biopsy needles back precisely to the area at which prior biopsy cores had been taken.
The authors state the following key results:
- In the first part of the study, 3D biopsy tracking was completed successfully in 82.6 percent of patients, with a success rate approaching 95 percent among the last 50 men.
- In the MRI fusion study, when suspicious lesions were targeted, a positive biopsy rate of 33 percent rate was found compared with a 7 percent positive biopsy rate for a standard, systematic, non-targeted biopsy (19/57 cores vs. 9/124 cores, P = 0.03).
- In the follow-up tracking study, Artemis demonstrated the ability to guide a biopsy needle back to within 1.2 ± 1.1 mm of a prior biopsy site, and this degree of accuracy appears to be independent of prostate volume or location of the biopsy site.
The application of this technology appears to show our increasing ability to identify areas of heightened risk for cancer within the prostate and to biopsy those areas with great accuracy. On the upside, such technology will lead to a lower risk for false negative biopsies. On the downside (if broadly adopted), it will significantly increase the cost of prostate biopsies and will place more men with potentially low-risk prostate cancer in the position of having to decide whether they are able to “live with” a small area of low-risk prostate cancer under active surveillance or whether they just want to “deal with it now” (with the concomitant risks for over-treatment of indolent disease).
It is clear that additional studies are going to be needed to define the absolute clinical value of this technology and whether it can really help physicians and their patients to increase acceptance of active surveillance and avoid the need for over-treatment. If all that technologies like this do is increase the risk for over-treatment because they help to identify even more cancer foci that would never actually lead to clinically significant disease, then one would have to question the real value of such technologies.