Can an advanced MRI improve prostate cancer screening?
Prostate cancer is notoriously tricky to detect. It often doesn’t cause symptoms until it’s advanced, and there are no routine imaging tests, like mammograms for breast cancer.
But a new study published in January 2017 in The Lancet showed promise for an advanced MRI to detect potentially aggressive prostate cancer, while also sparing some men from undergoing invasive biopsies.
After skin cancer, prostate cancer is the most common cancer in American men. According to the American Cancer Society, more than 160,000 new cases will be diagnosed in 2017 and nearly 27,000 men will die from the disease. The District of Columbia has one of the highest prostate cancer incidence rates in the country, with 120 out of 100,000 men getting the disease.
Our current prostate cancer screening process isn’t perfect. We hope this study is the first of many that leads to an improved standard of care.
How we screen for prostate cancer now
Most prostate cancers are first detected when a patient is found to have an elevated prostate-specific antigen (PSA), which is a blood test used for prostate cancer screening. The prostate is a walnut-sized gland that produces the fluid in semen. PSA is a protein made in the prostate, and elevated levels often are found in men with prostate cancer.
There has been some controversy about when men should get PSA tests, but we follow the guidelines of the American Urological Association, which recommend patients and their doctors discuss the test at age:
- 55-69 for men at average risk
- 40-54 for men at higher risk for prostate cancer, such as black men and men with a family history of prostate cancer
- 70 and older for men in excellent health with a 10- to 15-year life expectancy
While a PSA test can give us a clue that something may be wrong, it isn’t fool-proof. For example, the test can be elevated in patients who have benign enlargement of their prostate or prostatic inflammation. In such cases, the abnormal PSA test can lead to an unnecessary biopsy.
If your PSA levels are elevated, we’ll likely perform a transrectal ultrasound-guided (TRUS) prostate biopsy to gather small samples of the prostate to examine in the lab. We use a transrectal ultrasound to visualize the prostate. Then we insert a small needle into the gland to remove about 12 samples from different parts of the prostate.
Unfortunately, this approach is not perfect and can miss a significant cancer. If we suspect you have prostate cancer even after clear biopsy results, we may recommend a repeat biopsy or multi-parametric magnetic resonance imaging (MP-MRI), which may help to identify an occult site of prostate cancer that can then be targeted by a subsequent biopsy.
Study shows MRI can help detect prostate cancer more accurately
The January 2017 study looked at the effect of using an MP-MRI earlier in the prostate cancer screening process. MP-MRI uses the same machine as other MRI imaging, but differs in that it uses multiple, specific imaging sequences to make a diagnosis instead of one essential MRI sequence.
In the study, patients with an elevated PSA level underwent a MP-MRI before having a biopsy. The investigators then performed a standard TRUS biopsy on the patients, as well as a comprehensive “template” biopsy under anesthesia. This template biopsy was used as the “gold standard” for which to compare the performance of standard biopsy versus the MRI findings.
The results were fairly dramatic. The study found that 27 percent of patients did not have MRI findings that would warrant a biopsy. Thanks to the MP-MRI, one in four men would avoid an unnecessary biopsy. For the patients who did need a biopsy, the MRI-guided biopsy found 93 percent of aggressive cancers, compared with just 48 percent when the biopsy was done at random.
What does this mean for men today?
While the results of this study are promising, routine MP-MRIs to screen for prostate cancer are not ready for clinical practice just yet. However, it’s studies like this that eventually lead to new standards of care. We can imagine a day when routinely using MP-MRI is considered best practice, allowing us to specifically target our biopsies to areas of concern, or even considered “good enough” at diagnosing cancer so that we can skip the biopsy altogether and move straight to treatment.
While we won’t routinely be using MP-MRIs in the near future, if an informed patient asks for an MP-MRI early in the process, it’s reasonable to consider ordering one. And this study’s results may help us convince an insurance company to cover the cost.
Until we have further data confirming the accuracy of MP-MRIs to detect prostate cancer, we urge men to talk to their primary care physicians about the pros and cons of PSA testing and at what age they should consider it.
No imaging test is 100 percent perfect, but we’re working toward screening smarter. We hope in the future this process will be a win-win for patients and doctors as we catch more aggressive cancers and avoid unnecessary biopsies.
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