With most things in life, if you’re aiming for a target, you know where that target is. Whether you’re shooting for goal or swinging for a hole-in-one. But when doctors are trying to find cancer in your prostate, they’re effectively going in blind.
Can a new form of imaging, called multiparametric (mp) MRI, help doctors make sure they don’t miss life-threatening prostate cancer and help men avoid unnecessary biopsies? We investigate and speak to the experts.
One of the biggest problems we need to solve with prostate cancer is how to get better at diagnosing it. At the moment, if a man has higher than normal levels of prostate specific antigen (PSA) in his blood, this could suggest that he has something unusual going on with his prostate. But it takes a biopsy, where doctors use thin needles to take small pieces of tissue from the prostate, to actually find out whether there is any prostate cancer.
And even a biopsy isn’t fool proof. The most common procedure uses a trans-rectal ultrasound (TRUS) which can help guide the specialist to the prostate but can’t tell them where to find the cancer, if there is any. So the samples are taken randomly. This means that areas of aggressive cancer could get missed or tiny areas of non-aggressive cancer could get picked up, which could lead to unnecessary treatment. At the moment up to 30 per cent of tumours are missed.
Professor Mark Emberton, who is currently looking at using MRI before a TRUS biopsy to pin point where and if there is cancer, explains it like this: “Our current approach – a PSA test followed by TRUS biopsy – misses significant cancer far too often. It also misclassifies prostate cancer in about a third of men who are diagnosed. This misclassification is almost always in the direction of telling men they have low risk disease when they have not.
“The other problem is that random biopsy identifies a lot of disease that is insignificant. What we mean by this is tat men are told they have prostate cancer when actually that cancer is so small it cannot be felt by the finger, nor seen on any form of imaging."
A prostate biopsy is also an invasive procedure that carries risks for men. One third of men experience pain, fever, bleeding, infection, problems urinating or other issues after biopsy. And up to 3 in 50 men (6 per cent) may get a more serious infection. If there was a way for men to avoid a biopsy unless they really needed one, they'd also avoid these risks.
A new more accurate way of using MRI, called multiparametric (mp) MRI, may be able to help doctors find cancer before biopsy and help to guide the biopsy needles to where the cancer is. An mpMRI is made up of up to three different types of MRI scan which radiologists look at together to give a clearer picture of what’s going on in the prostate – such as if and where there might be a tumour.
Doctors could then be able to spot, and more accurately investigate, cancers that need treating – as well as ruling out the need for some men to have a biopsy in the first place. And Professor Emberton is positive about its future.
“I believe mpMRI will revolutionise diagnosing prostate cancer,” he told us. “This is a big moment – for the first time in history we can actually see the cancer we’re treating. On the other hand, we can also see – and show our patients – when there’s no cancer, which is reassuring.”
Professor Emberton is currently running a large scale trial, the PROMIS trial, looking at multi-parametric MRI. It is has been running since 2012, and is also looking at the cost-effectiveness of using mpMRI before biopsy – vital information if it is to become part of standard practice in the UK.
Although mpMRI may seem like an obvious next step in improving how men are diagnosed with prostate cancer, there are reasons why it isn’t standard practice.
Firstly it takes a good deal of skill and expertise to effectively produce and interpret mpMRI images and learning this takes time. Secondly, The National Institute for Health and Care Excellence (NICE) will need strong evidence that it works for it to be able to recommend using it in practice before biopsy. So, if mpMRI is really as effective as it is claimed, we hope that the data from Professor Emberton’s trial, which finishes in 2015, will provide this evidence.
“The results of the PROMIS study will be key,” says Dr Chris Parker, Consultant Clinical Oncologist at the Royal Marsden, who, like Professor Emberton, is optimistic about the difference that MRI could make to men being diagnosed with prostate cancer.
“PROMIS is currently recruiting over 700 men who are about to undergo their first prostate biopsy. In the study, men have a state-of-the-art multiparametric MRI scan prior to a comprehensive biopsy. The future of pre-biopsy MRI rests to a large extent on the results of this trial.”
In an update to its guidance earlier this year, NICE has in fact recommended that doctors consider using mpMRI for men who’ve already had a biopsy that hasn’t found cancer. This is a great step and could help men avoid more unnecessary biopsies by confirming that there is no significant cancer in their prostate.
And experts are also starting to talk about how it could be used in helping to better target and treat some types of prostate cancer. But it will take evidence of effectiveness and importantly cost-effectiveness, as well as significant investment in training, before multi-parametric MRI can truly make a difference to men being diagnosed with prostate cancer.
At our recent Research Forum we asked prostate cancer experts from around the world their thoughts on the future of mpMRI. The feeling was generally positive but also realistic. Professor Ken Muir, Professor of Epidemiology at the University of Manchester, summed it up like this, “Using imaging in prostate cancer is a really exciting development, but it’s still relatively new. Will it be able to do everything we hope? We’ll just have to wait and see.”