MRI scans can help around a quarter of men avoid prostate biopsy 

20/01/2017 00:00 
A trial led by the MRC Clinical Trials Unit at UCL and partly hosted at UCLH has shown that over a quarter of men with a clinical suspicion of prostate cancer could avoid a transrectal ultrasound-guided (TRUS) biopsy if they undergo a multi-parametric MRI (MP-MRI) scan first.

The Prostate MRI Imaging Study (PROMIS) also showed that the detection of aggressive cancers can be almost doubled by carrying out an MP-MRI, followed by a biopsy. This is because if the scan is suspicious, the MP-MRI can give information about where the cancer is and its size.

“The results of this study show clearly that having an MRI scan, followed by a TRUS biopsy if the scan is positive, can dramatically improve the diagnosis of prostate cancer."

Early prostate cancer produces no specific symptoms so men have a blood test called PSA (Prostate Specific Antigen). PSA is not specific to cancer, so if it is high, men currently undergo TRUS biopsies, whereby an ultrasound probe is inserted into the rectum and used to guide the biopsy needle into the prostate to take 10-12 small samples of tissue from the prostate. Of the approximate 100,000 men every year in the UK who have these biopsies, around 66% (66,000 men) are found to have no cancer or no life-threatening cancer.

TRUS biopsies are a relatively invasive procedure that can sometimes lead to side effects such as pain, bleeding, erectile dysfunction and infection. They can also be inaccurate because they only sample some areas of the prostate. TRUS biopsies are also taken in a random manner, so can pick up low-risk [harmless?] types of cancer that may never progress and spread. These men are then often treated unnecessarily.

The PROMIS study, published today in The Lancet, assessed the ability of MP-MRI to identify men who might safely avoid a biopsy. If the MP-MRI result was negative, doctors could then decide whether they should just monitor the patient’s PSA or discharge him altogether. If the MP-MRI result was positive, it might also be helpful in performing a better TRUS biopsy as the biopsy needles could be directed to areas of suspicion in the prostate.

PROMIS also found out how accurate MP-MRI was in comparison to TRUS biopsies at detecting important cancers. While it was already known that TRUS biopsies can miss clinically important tumours, the PROMIS study showed the extent to which this occurs.

The study, which involved 11 NHS hospitals, looked at 576 men with suspected prostate cancer. They were given an MP-MRI scan followed by two types of biopsy. The first of these was a template prostate mapping (TPM) biopsy, which was used as a control to compare the accuracy of the MP-MRI and standard biopsy against. This was followed by a TRUS biopsy.

The MP-MRI scans detected 93% of clinically important cancers.  The TRUS biopsies only identified 48% of clinically important cancers. Nine out of 10 men (89%) who had a negative MP-MRI scan, had either no cancer or a harmless cancer.

UCLH consultant Hashim Ahmed was one of the lead investigators on the study. He said: “The results of this study show clearly that having an MRI scan, followed by a TRUS biopsy if the scan is positive, can dramatically improve the diagnosis of prostate cancer. What’s more, combining MRI with biopsy could improve the detection of aggressive prostate cancers, reducing the need for repeat biopsies.

“It could also allow around a quarter of men with negative MRI scans to safely avoid having an immediate biopsy and the sometimes unpleasant side-effects these can cause,” Dr Ahmed said.

During the study, 44 men suffered a serious complication as a direct result of the biopsies. These included eight cases of sepsis and 58 cases of urinary retention.

The study was funded by the UK Department of Health, National Institute for Health Research, the UCLH Biomedical Research Centre and the Royal Marsden and Institute of Cancer Research Biomedical Research Centre. It was conducted by scientists from UCL, UCLH, the Royal Marsden Hospital, the MRC Clinical Trials Unit at UCL, the University of York and Hampshire Hospitals NHS Foundation Trust.

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