One in four men with suspected prostate cancer could avoid invasive and potentially dangerous biopsy if given an MRI scan first, according to a new study published today in The Lancet journal.
Researchers from University College London (UCL) in the UK estimate that adding the extra test could help 27 per cent men avoid an unnecessary biopsy and reduce the number of men who are over-diagnosed - diagnosed with a cancer that does not go on to cause any harm during their lifetime - by five per cent.
Typically, men undergo a biopsy of their prostate if they experience symptoms of prostate cancer or have a prostate specific antigen (PSA) test showing high levels of the PSA protein in their blood.
Each year, over 100,000 prostate biopsies are carried out in the UK and one million are conducted in Europe, researchers said.
However, the PSA test is not always accurate, which means that many men undergo unnecessary biopsies. "Prostate cancer has aggressive and harmless forms. Our current biopsy test can be inaccurate because the tissue samples are taken at random," said Hashim Ahmed from UCL.
"This means it cannot confirm whether a cancer is aggressive or not and can miss aggressive cancers that are actually there.
"Because of this some men with no cancer or harmless cancers are sometimes given the wrong diagnosis and are then treated even though this offers no survival benefit and can often cause side effects," said Ahmed.
Multi-parametric MRI (MP-MRI) scans provide information about the cancer's size, how densely packed its cells are and how well connected to the bloodstream it is, so could help differentiate between aggressive and harmless cancers.
In the new study, 576 men with suspected prostate cancer were given an MP-MRI scan followed by two types of biopsy in 11 National Health Service (NHS) hospitals in the UK.
Firstly, they underwent a template prostate mapping (TPM) biopsy, which was used as a control to compare the accuracy of the MP-MRI and standard biopsy against.
The second biopsy was the standard transrectal ultrasound-guided (TRUS) biopsy - the most commonly used biopsy for diagnosing prostate cancer.
The TPM biopsy found that less than half of the men in the study (40 per cent) had aggressive cancer.
Of these, the MP-MRI scan correctly diagnosed almost all of the aggressive cancers (93 per cent), whereas the TRUS biopsy correctly diagnosed only half (48 per cent).
Further, for men who had a negative MP-MRI scan, nine out of 10 (89 per cent) had either no cancer or a harmless cancer.
Because of this, the researchers suggest that MP-MRI could be used before TRUS biopsy to identify those who have harmless cancers and do not need a biopsy immediately.
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