About 25 percent of men may be spared invasive prostate cancer biopsies with just an MRI scan, a new study reports.
Currently, doctors recommend biopsy exams for men who have suspected prostate cancer, either because they have high prostate specific antigen levels or have other symptoms related to the prostate. The biopsy involves twelve needle samples, taken at random from the prostate. This invasive procedure is painful, risky, and imperfect. In the worst case, the biopsy can miss cancer that’s present. And equally bad, the cancer is not present and the invasive procedure could have been prevented.
"Prostate cancer has aggressive and harmless forms. Our current biopsy test can be inaccurate because the tissue samples are taken at random. This means it cannot confirm whether a cancer is aggressive or not and can miss aggressive cancers that are actually there,” explained Hashim Ahmed, the study’s co-chief investigator. "Taking a random biopsy from the breast would not be accepted, but we accept that in prostate,” he added, further noting the imperfect nature of this diagnostic test.
“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. On top of these errors in diagnosis, the current biopsy test can cause side effects such as bleeding, pain and serious infections," Ahmed said.
To improve on the diagnosis of prostate cancer, the team studied 576 men with suspected prostate cancer. These men were given MRI scans in addition to two types of biopsy exams.
They researchers found that the MRI scan offered a high level of sensitivity – it correctly picked up 93 percent of aggressive prostate cancers. By contrast, the standard transrectal ultrasound-guided (TRUS) biopsy only picked up 48 percent correctly. In addition, the MRI scan also showed high specificity (89 percent), correctly identifying cases where there were no cancer or the cancer was harmless.
Strikingly, using the MRI scan revealed that around 27 percent of the men didn’t need to undergo biopsy exams at all. "Our results show that MP-MRI should be used before biopsy. Our study found that using the two tests could reduce over-diagnosis of harmless cancers by 5%, prevent one in four men having an unnecessary biopsy, and improve the detection of aggressive cancers from 48% to 93%," said Dr. Ahmed.
"While combining the two tests gives better results than biopsy alone, this is still not 100% 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."