An MRI Could Help a Quarter of Men Avoid Prostate Biopsies

The latest in the prostate-cancer debate.

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Jan 19 2017, 11:31pm

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A new study suggests that MRI scans could improve prostate cancer diagnosis rates and save one in four men from having unnecessary and, ahem, invasive biopsies.

Men with prostate symptoms often get a prostate specific antigen (PSA) test along with a digital rectal exam ("digital" here refers to the doctor's finger, not a computerized butt scan). PSA is a protein produced by the prostate and the test looks for how much of this protein is found in the blood. While men with prostate cancer often have high PSA levels, just having an abnormal test doesn't necessarily mean you have prostate cancer; it could mean you have an inflamed or enlarged prostate, so a biopsy would follow to confirm the test results. But even if the biopsy says it's cancerous, it may not even mean that treatment is required because some forms of prostate cancer are harmless and may grow so slowly that they'll never cause problems. Treatment for prostate cancer, including surgery and radiation, can have life-altering side effects like erectile dysfunction, urinary incontinence, and bowel problems, so misdiagnosis is a big deal.

A group of British researchers wanted to determine who could safely avoid biopsy by getting an MRI scan first. For a study in The Lancet, they rounded up 576 men with suspected prostate cancer (either because they had elevated PSA levels, suspicious exams, or a family history of the disease) and had them get MRIs followed by two kinds of biopsies before comparing the results. The MRIs would be able to show the cancer's size, how well connected it is to the bloodstream, and how densely packed the cells are—basically, it would help doctors determine if the cancer is aggressive or harmless.

The first biopsy was used as a control to compare the MRI and the second biopsy against (the second one is the most commonly used). The control biopsy found that 40 percent of the men had aggressive prostate cancer. Among these men, the MRI had correctly diagnosed 93 percent of them compared to just a 48 percent success rate for the second biopsy. In the men who had a negative MRI scan, 89 percent had either no cancer or a harmless cancer.

The authors say their findings suggest that MRI should be used before the standard biopsy to weed out the men who have harmless cancers and don't need biopsies immediately, or ever. Instead, these men could be great candidates for a watchful waiting approach. "Our study found that using the two tests could reduce over-diagnosis of harmless cancers by 5 percent, prevent one in four men having an unnecessary biopsy, and improve the detection of aggressive cancers from 48 percent to 93 percent," lead study author Hashim Ahmed, a urologist at University College London Hospital, said in a release.

For those whose MRIs point to cancer, the biopsy should still follow, but having the MRI results could help doctors figure out exactly which parts of the prostate to look at. "While combining the two tests gives better results than biopsy alone, this is still not 100 percent accurate so it would be important that men would still be monitored after their MP-MRI scan. Biopsies will still be needed if an MP-MRI scan shows suspected cancer too, but the scan could help to guide the biopsy so that fewer and better biopsies are taken," Ahmed added. This combo approach could help diagnose up to 18 percent more cases of aggressive cancer.

The authors acknowledged that since the standard biopsy was done second, swelling and changes to the prostate tissue could have affected its accuracy and they said more research is needed to determine if the MRI approach is more cost-effective than biopsy alone. But this is welcome news for anyone facing the prospect of having a dozen chunks of tissue cut out of their groin.

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