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Combining tests more accurately diagnoses prostate cancer

The study showed that doctors could more accurately diagnose prostate cancer by combining two tests.Monkeybusinessimages / iStock / Getty Images Plus

Prostate cancer is the most common cancer among men in the United States and the second leading cause of male cancer deaths. But prostate cancer can vary widely in severity and its potential to spread.

Low-grade prostate cancer is associated with a very low risk of cancer-specific death and often doesn’t require treatment. High-grade cancers are much more likely to spread and are responsible for most prostate cancer deaths. This makes the correct assessment of the cancer grade very important for treatment decisions. Finding and treating cancers before symptoms occur may improve men’s health or help them live longer.

Systematic biopsy is often used to diagnose prostate cancer. This is a non-targeted method of taking systematically spaced samples across the prostate gland to find a cancer. Because this method can potentially miss areas of cancer, doctors may then overtreat a patient with low-grade disease, fearing there is high-grade disease they missed. Or, if an aggressive cancer is missed, a patient may be undertreated.

MRI-targeted biopsies, which combine MRI images of suspected cancer with real-time ultrasound technology to target areas for biopsy, are better able to detect more high-grade cancers than systematic biopsies. A team led by Dr. Peter A. Pinto at NIH’s �����鶹��Ƶ Cancer Institute (NCI) carried out a study to determine whether it would be better to replace systematic biopsy with MRI-targeted biopsies or use both tests together. They compared these methods on more than 2,100 men who had MRI-visible lesions. The study was funded in part by NCI and NIH’s Clinical Center. Results were published on March 5, 2020, in the New England Journal of Medicine.

This 3-D map illustrates MRI-targeted biopsies and systematic biopsies in a prostate.�����鶹��Ƶ Cancer Institute

Participants underwent both MRI-targeted and systematic biopsies. More than 1,300 were diagnosed with cancer and 404 underwent prostatectomy, a full removal of the prostate. By comparing diagnoses from systematic biopsy alone to systematic biopsy plus MRI-targeted biopsy, the researchers found that combining the methods led to 208 more cancer diagnoses than systematic biopsy alone. The addition of MRI-targeted biopsy also led to 458 upgrades—changes in diagnosis to a more aggressive cancer, based on analysis of the biopsy tissue.

The combined biopsy provided more accurate diagnoses. Among the men who underwent prostatectomy, systematic biopsy alone underdiagnosed about 40% of the cancers. MRI-targeted biopsy alone underdiagnosed about 30%. The combined biopsy underdiagnosed only 14.4%. For the most aggressive cancers, systematic biopsy underdiagnosed 16.8% and MRI-targeted biopsy 8.7%, but combined biopsy underdiagnosed only 3.5%.

“Prostate cancer has been one of the only solid tumors diagnosed by performing systematic biopsies ‘blind’ to the cancer’s location. For decades this has led to the overdiagnosis and subsequent unnecessary treatment of non-lethal cancers, as well as to missing aggressive high-grade cancers and their opportunity for cure,” says Pinto. “With the addition of MRI-targeted biopsy to systematic biopsy, we can now identify the most lethal cancers within the prostate earlier, providing patients the potential for better treatment before the cancers spread.”