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Targeted fusion-guided biopsy improved detection of high-risk prostate cancers
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Targeted magnetic resonance/ultrasound fusion prostate biopsy detected significantly more cases of high-risk prostate cancers than standard extended-sextant biopsy in men undergoing biopsy for suspected prostate cancer, according to study results.
“This study demonstrates that targeted fusion-guided biopsy could significantly enhance our ability to identify patients with high-risk prostate cancers that need more aggressive treatment,” researcher Mohummad Minhaj Siddiqui, MD, assistant professor of surgery at the University of Maryland School of Medicine and director of urologic robotic surgery at the University of Maryland Marlene and Stewart Greenebaum Cancer Center, said in a press release. “With fusion technology, we now have a tool to help us differentiate high-risk cancers from low-risk ones that may require minimal or no treatment. There is a concern that we over-diagnose and over-treat low-risk cancers that are unlikely to be terminal, and this technology enables us to make a more reliable diagnosis than the current standard practice.”
Siddiqui and colleagues evaluated data from 1,003 men who concurrently underwent targeted and standard biopsy at the NCI. All patients had elevated PSA levels or abnormal digital rectal examination results.
Eight more prostate cancers were detected through standard vs. targeted biopsy (469 vs. 461). There was agreement in the biopsy results in 690 (69%) men.
Thirty percent more high-risk cancers were detected using the targeted magnetic resonance/ultrasound fusion prostate biopsy than the standard extended-sextant biopsy (173 vs. 122; P˂.001). However, the targeted biopsy detected 17% fewer low-risk cancers than the standard biopsy (213 vs. 258; P=.002).
“This study demonstrates that the MRI/ultrasound fusion biopsy technique offers benefits when compared to the current standard of care to diagnose clinically significant prostate cancer,” E. Albert Reece, MD, PhD, MBA, vice president for medical affairs at the University of Maryland and the John Z. and Akiko K. Bowers distinguished professor and dean of the University of Maryland School of Medicine, said in the release. “Although further research is needed, this method holds promise, especially for diagnosing men with high-grade, aggressive cancers that may go undetected.”
The combination of the results from the targeted and standard biopsy approaches compared with the targeted approach alone led to the detection of an additional 103 prostate cancers. A majority of these were low-risk cancers (83%), whereas 12% were intermediate risk and 5% were high risk.
Researchers compared whole-gland prostatectomy pathology results with biopsy results in a subset of 170 men. The sensitivity of the preoperative targeted biopsy to predict whole-gland pathology was 77%, whereas the sensitivity for the standard biopsy was 53%. However, the specificities were similar between the targeted and standard biopsy approaches (68% vs. 66%).
The area under the curve (AUC) for the targeted biopsy was 0.73, which was significantly greater than the AUC for the standard (0.59; P=.005) and combined (0.67; P=.04) approaches.
“While these findings could translate into substantial benefit to patients, this study is preliminary with regard to clinical endpoints such as recurrence of disease and prostate cancer-specific mortality,” Siddiqui said.
More research is needed before the targeted biopsy should be widely applied to clinical practice, Lawrence H. Schwartz, MD, of the department of radiology at the Columbia University College of Physicians and Surgeons, and Ethan Basch, MD, of the Lineberger Comprehensive Cancer Center of the University of North Carolina, wrote in an invited commentary.
“Any test that can inform decision making and potentially spare patients harm is immediately appealing, even if the effect on clinical outcomes is unknown,” Schwartz and Basch wrote. “Nonetheless, a new test should not be widely adopted in the absence of direct evidence showing the benefits on quality of life, life expectancy or ideally both. Therefore, the scientific community has the responsibility to ensure through clinical research that promising new technologies such as the magnetic resonance/ultrasound fusion imaging-guided biopsies bring value to patients.”
For more information:
Schwartz LH. JAMA. 2015;313:367-368.
Siddiqui MM. JAMA. 2015;313:390-397.
Disclosure: The researchers report holding patents for the magnetic resonance/ultrasound fusion biopsy platform and other biopsy-related technologies. Schwartz reports honoraria from Pfizer, as well as service on data and safety monitoring and endpoint analysis committees for BioImaging, Celgene, Icon and Novartis.
Perspective
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Matthew J. Resnick, MD, MPH
Siddiqui and colleagues evaluated the performance of magnetic resonance (MR)-fusion biopsy compared with standard ultrasound-guided biopsy in the diagnosis of prostate cancer. The majority of patients in the cohort had undergone prior prostate biopsy. Despite similar rates of overall cancer detection, there were important differences in the distribution of risk associated with the tumors identified by each modality. MR fusion was associated with increased detection of high-risk tumors, with concomitant decreased detection of low-risk tumors.
This study has important implications with respect to optimizing the ratio of benefit to harm associated with prostate cancer diagnosis. There are two important limitations to the current paradigm of prostate cancer diagnosis. These include the risk for prostate cancer overdetection — or the identification of disease that is unlikely to result in morbidity or mortality — as well as underdetection of clinically significant prostate cancer with routine ultrasound-guided prostate biopsy.
The study by Siddiqui and colleagues suggests that MR-fusion biopsy may serve to address both of these limitations. MR-fusion biopsy was associated with a 30% increase in the detection of high-risk prostate cancers and a 17% reduction in the detection of low-risk prostate cancers compared with standard ultrasound-guided biopsy.
Given appropriate concerns surrounding prostate cancer overdiagnosis, the use of MR-fusion technology may indeed facilitate identification of prostate tumors that merit treatment, thereby sparing patients from the anxiety associated with diagnosis of low-risk prostate cancer. Additionally, and importantly, minimizing prostate cancer overdetection ultimately may reduce the significant morbidity of definitive treatment among those patients with low-risk disease who elect to be treated.
Although these data are certainly promising, there remain a number of unanswered questions with respect to the ubiquitous use of MR-fusion technology. Omission of standard biopsy templates does appear to preferentially reduce the risk for identifying low-risk disease, but it also was associated with failure to identify a proportion of high-risk tumors. Identifying the optimal threshold of discrimination between identification of high-risk disease and failure to detect low-risk disease remains a challenge, and it likely is predicated on individual patient preferences and utilities.
Additionally, the optimal role of MR-fusion biopsy remains largely unknown. The current study cohort was heavily pre-biopsied, and accordingly, these results may reflect some degree of selection bias associated with negative index prostate biopsy. As such, additional work must be done to elaborate the performance of MR-fusion compared to standard biopsy in various populations given the significant incremental cost associated with the technology. Doing so will ultimately optimize the value of care we are able to deliver to patients.
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