In 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.
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.
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