MRI Conspicuity of Prostate Cancer: Investigating Clinically Significant Prostate Cancer Not Detected by Multiparametric MRI

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In the UK, the burden of prostate cancer continues to saw. Over 47,000 men are diagnosed with the disease each year and it has recently overtaken breast cancer in terms of cancer-related deaths. However, the severity of prostate cancer varies greatly, and in order for men to receive the most appropriate treatment, it is essential that they be given a timely and accurate diagnosis.Traditionally, prostate cancer is diagnosed in men with an abnormal blood test (prostate specific antigen; PSA) or an abnormal feeling prostate, after an examination through the back passage. These men then undergo a biopsy, in which samples of prostate tissue are taken. These samples are analysed under the microscope to assess for the presence or absence of prostate cancer. The location of where samples are taken from is not influenced by knowledge of where the cancer is, and the standard way in which the biopsies are taken is often termed 'random.' Random biopsy risks missing aggressive prostate cancer and risks diagnosing prostate cancers that are not very aggressive at all (thereby triggering treatment, when it is not needed). To overcome this haphazard approach, we have now begun to introduce MRI scans before men have their prostate biopsied. This has brought a collection of benefits, including being able to see whether a cancer is present or not (and therefore whether a man needs a biopsy or not) and also seeing where the cancer is, how large it is, and how many tumours are present. The advantages are clear, and two large recent research studies have shown that MRI scans are highly accurate at detecting cancer, and can help save many men from painful biopsies which carry risks such as blood in the urine, blood in the semen and infection requiring admission to hospital. These research studies have also shown that by using new MRI scans to help guide where we biopsy, we are able to pick-up more of the aggressive cancers and less of the non-aggressive cancers (compared to the traditional approach).These findings are very encouraging for the future, however, there are still occasions in which MRI scans can miss prostate cancer, and the reason this happens is not well understood. The main aim of our research is to discover and understand which prostate cancers are not detected by MRI. If we can understand the features that these cancers have, we may be able to work out reasons that they are not detected. We may also be able to make a decision about whether or not this truly matters - it is possible that MRI only misses non-aggressive cancers that we do not need to be concerned about. On the other hand, if MRI scans miss aggressive cancer, then this could be a serious problem, as the cancer would be liable to spread before it is detected. The truth is, we do not know a lot about these prostate cancers, and so there is a very strong need for this research.This research project will be conducted at University College London, which is world-respected in this field. The plan is to look carefully, in different ways, at cancers that are not detected. By scrutinising their MRI scans and biopsies, we hope find out their characteristics, and ultimately, reasons for why they were overlooked in the first place. Building on this, we then may even be able to work out additional ways to find these tricky tumours.In addition to occasionally missing prostate cancer, MRI does have another problem. Roughly half of all cases that are suggestive of cancer on MRI turn out to be benign conditions on biopsy. Traditionally this is attributed to infection, however, the true reasons for this have not been clearly explained. So in addition to the cancer that is missed, this study will examine cases in which the MRI scan showed cancer to be present, but that in actual fact was not there when the prostate was biopsied. We will examine these cases carefully to help find out what aspects caused an inappropriately suspicious appearance on MRI. Again, if we can do