Feature Article

MRI Evolving to Solve a Prostate Cancer Riddle

The Problem

Although prostate cancer is in the top three causes of cancer death for men in the U.S., the statistic belies a truth – the death ratio is low. Although about one in seven men will be diagnosed, only one in 39 will die from the disease. This riddle is further complicated by the fact that prostate cancer is a common symptom of aging. One in three men between the age of 50 and 70 have cancer cells present in the prostate. Further, 80 percent have cancerous cells present by age 80. It turns out that the longstanding challenge of diagnosing and treating prostate cancer is figuring out which three percent of men - especially young men -  are at risk of dying from the disease. Unnecessary treatment for men not at immediate risk carry significant unwelcome side effects. These range from incontinence, bowel problems, and impotence, not to mention the cost of unneeded treatments. 

MRI Research Seeks to Find an Answer

Better medical insight is needed to sort out low-grade from high-grade prostate cancer threats. There is significant recent progress to report on this front – and MRI imaging is at the forefront. In fact, there appears to be a worldwide effort on finding better ways to solve the prostate cancer riddle with MRI diagnostic applications. 

A study in the Journal of the American Medical Association 1 concluded that an MRI-derived predictive model could significantly reduce unneeded prostate biopsies, while still diagnosing significant cancers. The exams were conducted in conjunction with MRI-transrectal ultrasound (TRUS), which improved detection of prostate cancer. While the researchers were unclear whether the MRI itself added additional value to the multivariable prediction model, the results were encouraging. The findings strongly suggest that MRI, applied with the new protocols, may be an underutilized tool in sorting out which men are at increased risk of developing and dying from aggressive cases of the disease.

Reducing Biopsies With MRI

In a published study in The New England Journal of Medicine, 2  a team of English and European researchers found that TRUS is not necessarily required to sort out risk factors of prostate cancer. MRI in conjunction with or without biopsy is capable of spotting elevated levels of prostate-specific antigen levels to determine a risk-assessment on patients. 

In this study, patients were randomly split into two groups, one a MRI-targeted group. The study team concluded that noninvasive MRI, with or without targeted invasive biopsy, was non-inferior to standard biopsy. The authors noted there was no comparative data available, suggesting an opportunity for other researchers to verify the findings. The sponsors said the sizeable international study found that an MRI scan protocol could cut prostate cancer biopsies by 28 percent.

The study achieved the goal of sorting out which diagnosed cancers were life-threatening (i.e., more harmful prostate cancers) and which were less threatening cases (i.e., slow developing cases). The team concluded that a quarter of the one million European men who currently undergo a biopsy for prostate cancer diagnosis could safely avoid it if they had access to high-quality MRI services. 

A third recent study3 at the University of Cincinnati appearing in the online edition of the Journal of Urologic Oncology established the superiority of MRI fusion biopsy to standard prostate biopsy. The study, which the researchers say is one of the largest of its kind, involved nearly 800 patients at four U.S. research health systems. Using an MRI/ultrasound infusion biopsy method, the researchers were seeking to find a better protocol to classify prostate cancer. According to the research team, the current protocol standard and saturation biopsy method result in both underdiagnoses of significant cancer and overdiagnosis of insignificant cancers with a general unacceptable level of false-positive findings. The team concluded the MRI/ultrasound infusion biopsy outperformed standard biopsy in men who had never before received a biopsy.

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New and Ongoing MRI Trials Underway to Improve Care 

Other MRI/prostate cancer trials are in progress.4 In April 2018 the Medical Research Council (MRC) and Cancer Research U.K. announced a nearly $7 million study intended to evaluate the possibility that MRI could replace invasive biopsies as the standard in diagnosing prostate cancer. The RE-IMAGINE study plans to incorporate machine learning, or artificial intelligence, and genomics to determine the volume and location of the cancer.

The study sponsors note that surgical biopsy causes side effects such as pain, bleeding, urine retention and even sepsis. And prostate-specific antigen (PSA) tests have been proven to be unreliable for population screening – a cornerstone strategy in making healthcare more clinically and economically efficient. In the U.K., PSA tests have resulted in a 75 percent rate of false positives and a 15 percent rate of false negatives.

The goal of the RE-IMAGINE study will be to trial MR and other higher-tech tests on 1,000 men with medium to high-risk cancers to predict better prostate cancer progression. The study will build on work published last year in The Lancet that concluded MRI scans were capable of ruling out disease in 27 percent of men who received a positive PSA result.

U.S. studies are also in progress. According to clincaltrials.gov 5, there are over 250 studies involving MRI. Among the active studies are two trials recruiting patients to compare the sensitivity of MRI compared to PET for highlighting nuclear medicine tracers in prostate tumors. Another study will seek to determine the effectiveness of MRI in detection, staging, and management of prostate cancer compared to biopsy. Yet another trail is underway to learn, with MRI screening,  in which men are best recommended for active surveillance to monitor slow-progressing prostate cancer.

1 - "A Magnetic Resonance Imaging-based Prediction Model For Prostate Biopsy Risk Stratification." JAMA Oncology.  https://jamanetwork.com/journals/jamaoncology/article-abstract/2673079 . Accessed June 4. 2018.

2 -  "MRI-Targeted or Standard Biopsy for Prostate-Cancer Diagnosis."  The New England Journal of Medicine.    https://www.nejm.org/doi/full/10.1056/NEJMoa1801993. Accessed June 4, 2018.

3 - "Fusion prostate biopsy outperforms 12-core systematic prostate biopsy in patients with prior negative systematic biopsy: A multi-institutional analysis" Urologic Oncology. https://www.urologiconcology.org/article/S1078-1439(18)30124-8/fulltext . Accessed June 4, 2018.

4 - https://www.dotmed.com/news/story/42430

5 - MRI/prostate cancer trail search. ClinicalTrials.gov. https://clinicaltrials.gov/ct2/results?cond=Prostate+Cancer&term=MRI&cntry=US&state=&city=&dist= . Accessed 6/4/2018.