MRI helps diagnose prostate cancer more accurately

Date: Mar-27-2014In a world first, an Australian clinical trial has shown that biopsy guided by MRI

can significantly improve the diagnosis of life-threatening prostate cancer and reduce the

over-diagnosis of non-life-threatening cases, thus avoiding the side effects of unnecessary

treatment.

At present, to find out if he has prostate cancer - following a test that shows he has raised

prostate-specific antigen (PSA) levels - a man has to undergo a painful procedure called

transrectal ultrasound guided biopsy (TRUSGB) that involves taking up to 30 random needle

biopsies of his prostate through the rectum.

With the new MRI-guided system, doctors first do an MRI scan and get a better idea of where

a tumor might be located in the prostate.

Then, if the scan indicates a need for it, they just

take two needle samples of that area, sparing the need for multiple biopsies.

The new system uses a method called multi-parametric magnetic resonance imaging (mpMRI).

mpMRI will reduce over-treatment of non-life-threatening prostate cancer

Urologist Dr. Les Thompson, who led the 2-year clinical trial at Brisbane's Wesley

Hospital, says:

"This is a significant improvement in terms of accuracy and in reducing discomfort for

patients and spares many men the burden of multiple prostate biopsies."

"This latest mpMRI imaging technique will reduce over-treatment of men with non-life-threatening prostate cancer, avoiding the possible side-effects of treatment," he adds.

He and his colleagues report, in the journal European Urology, how the trial showed

that use of mpMRI:

Halved (reduced by 51%) the number of men needing prostate biopsies
Showed a 92% sensitivity in diagnosing life-threatening disease (compared with the current

leading method TRUSGB, which has only a 70% sensitivity in diagnosing life-threatening prostate

cancer)
Cut the problem of over-diagnosis of non-life-threatening prostate cancer by around

90%.

The trial enrolled 223 patients with raised PSA levels. All of the patients underwent both

diagnostic procedures: the standard TRUSGB, and the new method where an mpMRI scan is done

first, and then only those patients whose MRI image points to high-risk prostate cancer undergo

MRI-guided biopsy.

mpMRI uses three parameters to image the prostate

Co-investigator Dr. Rob Parkinson, a specialist radiologist at the hospital, says that mpMRI

uses three parameters when scanning the prostate, and that:

"Diffusion-weighted imaging, one of these three parameters, assesses movement of water

molecules within tissues. An imaging map is mathematically generated from this information, and

prostate cancer is evident as a dark area."

In TRUSGB, which uses ultrasound to guide biopsy sampling, the core samples are random and

taken from all areas of the prostate, but, when biopsies are done following a prostate mpMRI,

"you know where the tumour is located and thus where to direct the biopsy needle," he

explains.

One of the issues that is bound to be raised in deciding how to proceed with the new system

as a diagnostic tool is the higher costs associated with MRI.

According to a report in The

Australian news channel, Dr. Thompson says he is campaigning to get it listed as a medicare

item like mammograms for breast screening.

Campaigners say the cost is small compared with the social and emotional costs of misdiagnoses

that occur with the current method.

According to the American Cancer Society, prostate cancer occurs mainly in older men - around

6 in 10 cases are diagnosed in men aged 65 and over. About 1 man in 7 will be diagnosed with

prostate cancer during his lifetime.

Prostate cancer is the second leading cause of cancer death in American men, behind only lung

cancer. However, although it is a serious disease, most men diagnosed with prostate cancer do

not die from it. There are currently 2.5 million men in the US living with prostate

cancer.

The study was sponsored by the Wesley Research Institute and the Thorsen Foundation.

Medical News Today recently learned about a study where researchers in the UK found

a possible biomarker that could help improve early diagnosis of prostate

cancer. They believe their findings, published in the journal Prostate, could lead

the way to better tools for the early diagnosis of prostate cancer.

Written by Catharine Paddock PhD




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