MRI Scans Reduce Unnecessary Biopsy in a Quarter of Men with Suspected Prostate Cancer

One of every 4 men with suspected prostate cancer could avoid unnecessary biopsies and overdiagnoses by undergoing an MRI scan first.

Multi-parametric MRI (MP-MRI) scans are used to distinguish between harmless and aggressive cancers by providing information about the cancer’s size, density, and how well it is connected to the bloodstream.

Men who experience symptoms of prostate cancer, or who have high levels of PSA, typically undergo a biopsy. However, the PSA test is not always accurate, and results in unnecessary biopsies.

A study published in The Lancet included 576 men suspected of prostate cancer. The participants were given an MP-MRI scan followed by 2 different types of biopsy in 11 NHS hospitals. A template prostate mapping (TPM) biopsy was used as a control to compare the accuracy of the MP-MRI with the standard biopsy. The second biopsy was the standard transrectal ultrasound-guided (TRUS) biopsy, most commonly used for diagnosing prostate cancer.

The results of the TPM biopsy showed less than half of the participants had aggressive cancer. The MP-MRI scan accurately diagnosed almost all of the aggressive cancers (93%), whereas, the TRUS biopsy correctly diagnosed half (48%).

Of the men with a negative MP-MRI scan, 89% had either no cancer or a harmless cancer, the study found.

“Prostate cancer has aggressive and harmless forms,” said lead author Dr Hashim Ahmed. “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. 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 [adverse events]. On top of these errors in diagnosis, the current biopsy test can cause [adverse events] such as bleeding, pain, and serious infections.”

The study findings suggest that MP-MRI could be used before TRUS biopsy to identify patients with harmless cancers who do not require an immediate biopsy. Instead, the authors recommend that physicians continue to monitor these patients, while those believed to have aggressive cancers have their MP-MRI scan results confirmed by the TRUS biopsy.

There were 44 serious adverse events that occurred during the study due to the biopsies, with 8 cases of sepsis caused by urinary tract infection and 58 cases of urinary retention. A limitation to the study was that the TPM biopsy was given before the TRUS biopsy, which may have caused swelling and changes in the prostate tissue that could affect the accuracy of the TRUS biopsy.

“Our results show that MP-MRI should be used before biopsy,” Dr Ahmed said. “Our study found that using the 2 tests could reduce overdiagnosis of harmless cancers by 5%, prevent 1 [of] 4 men having an unnecessary biopsy, and improve the detection of aggressive cancers from 48% to 93%.

“While combining the 2 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.”

The authors noted that more research needs to be done on the cost-efficacy of the approach, how it affects hospital capacity, and ensuring there are enough radiologists to conduct the MP-MRI.