The search for an equivalent of the mammogram to screen for prostate cancer is a step closer as researchers demonstrate the potential of a new short MRI scan.
The big challenge in creating a screening programme for the disease is detecting dangerous cancers without leading to more men needing biopsies. As biopsies are painful and risk causing an infection, tests need to minimise the number of false positives.
The current first-line test for prostate cancer offered by GPs detects levels of the protein PSA in the blood. However, this has a high false-positive rate.
The new 15-minute scan, dubbed a prostagram, does not lead to more men having a biopsy than the PSA test, and it appears to be better at detecting aggressive cancers. Over 400 men were screened in the trial, and 11 cases of clinically significant cancer were seen by MRI, while only 7 were seen with PSA. The prostagram will need to be tested in a larger trial with thousands of men screened to verify its improved detection.
Prostate cancer has a high survival rate if it is caught early, however many men do not experience symptoms until the cancer has spread and is incurable. It is hoped that a screening programme would catch aggressive cancers before this stage.
The trial led by researchers at Imperial College London was part-funded by TUF, enabling the scans to be tested in a second centre at Mount Vernon Hospital to verify its generalisability.
The trial compared different thresholds for the MRI scan to define a positive case. Each scan was graded out of five, and the researchers found that a score of four or higher avoided too many men needing a biopsy unnecessarily.
“With a score of 4-5, you would biopsy the same number of men as PSA, but PSA was missing a number of aggressive cancers. The MRI identifies a good proportion of these cancers and seemed to be more accurate than PSA,” says Dr David Eldred-Evans, the lead author of the study and research fellow at Imperial.
A prostagram scan would be more costly than a PSA test, however David hopes that its improved accuracy would make up for that: “If you have to do it less frequently, even though the test is more expensive, it can become cost-effective.”
