In a new study, researchers have shown that the best way to predict the future risk of prostate cancer is by starting out with an MRI-guided prostate biopsy.
The research was conducted by a team of UCLA physicians.
Every year, tens of thousands of men in the United States are diagnosed with low-risk prostate cancer.
Prostate cancer is typically detected with a blood test measuring levels of prostate-specific antigen, or PSA.
However, elevated PSA levels detect not only aggressive prostate tumors but also very slow-growing cancers that are unlikely to become life-threatening.
Most men are told that they don’t need treatment other than “active surveillance” to monitor their slow-growing tumors.
Men with higher than usual PSA levels are referred to get a biopsy, in which cells are collected from the prostate to reveal more details about a tumor.
In the past, doctors relied on ultrasound to guide a biopsy needle into the prostate.
However, ultrasound doesn’t allow the visualization of prostate tumors, so a biopsy may have missed a tumor.
Over the past decade, it’s become possible to instead perform an MRI-guided biopsy.
MRI, or magnetic resonance imaging, lets doctors see the majority of prostate tumors and take a biopsy from the exact location of cancer within the prostate.
The group earlier had reported that combining MRI-guided biopsies with a more traditional approach of sampling throughout the prostate detects more cancers than either approach alone.
In the study, the team analyzed data on 332 men with low prostate cancer risk, all of whom received an initial MRI-guided biopsy and at least one follow-up biopsy an average of 3.9 years later.
The researchers found that when a man’s prostate tumor had a Gleason Score of 7 at the time of an MRI-guided biopsy, there was a three-and-a-half-times greater risk that the man would develop a higher-risk cancer compared to men who had a negative biopsy.
The Gleason Score is a grading system used to determine the aggressiveness of prostate cancer.
A score of 6 is generally considered low-risk cancer recommended for active surveillance, while a score of 7 or more may require radiation or surgery.
Moreover, combining an MRI-guided biopsy with the more standard approach of taking a systematic sampling of biopsies from around the prostate boosted the likelihood that a positive initial biopsy result was truly positive.
The team says when doctors use an MRI-guided biopsy to confirm what appears to be low-risk prostate cancer, they can then tell the patient with pretty good accuracy what the future is going to entail and what his risks are of having cancer that will require treatment in the future.
While MRI-guided biopsy is being used, it is still not being very widely used and these results have the potential to establish a new standard for using it in active surveillance.
The lead author of the study is Dr. Leonard Marks.
The study is published in JAMA.
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