Preoperative MRI in Women With Dense Breasts is Associated With Higher Biopsy Rates Without a Concomitant Increase in Cancer Detection Rates

A new BCSC study indicates that pre-operative MRIs increase both additional biopsy and cancer detection in women, but women with higher breast density experience an additional increase in biopsy rates without a corresponding increase in cancer detection rates

Posted by Tracy Onega at 10:00 AM on Nov 17, 2021


A new BCSC study using data from women participating in the national Breast Cancer Surveillance Consortium (BCSC) has been able to shed some light on the question of whether pre-operative MRI is useful for women newly diagnosed with breast cancer, and what some of the tradeoffs might be.  Among almost 20,000 women with a new breast cancer diagnosis, 28% of them had MRI as part of their workup prior to surgery. MRI is able to “see” what’s in breast tissue better than mammography, so the idea with pre-operative MRI is that the extent of the breast cancer, and possibly new spots of cancer will be found, allowing for better treatment and avoiding multiple surgeries. That makes sense but hasn’t been shown, especially for women with dense breasts, which are harder to “see” into on breast imaging.  This new study found that four times as many women with MRI had additional breast biopsies before their surgery to treat the cancer (22.6% v. 5.1%). While that doesn’t sound like something women would want, the additional cancers detected were also four times higher for women who underwent MRI compared with those who didn’t (9.9% v. 2.6%), suggesting that MRI is finding more of the cancer that is there and thus can be surgically removed. For women with dense breasts, however, there were more additional biopsies with no additional cancer found. So, in a nutshell – this biggest study of its kind found that pre-operative breast MRI finds more cancer in the breasts compared to mammography. However, women with dense breasts don’t seem to gain a specific advantage over women with lower density breasts when using MRI pre-operatively.

Onega T, Zhu W, Kerlikowske K, Miglioretti DL, Lee CI, Henderson LM, Tosteson ANA, Wernli KJ, diFlorio R, Weaver DL, Buist DSM. Preoperative MRI in breast cancer: effect of breast density on biopsy rate and yield. Breast Cancer Res Treat. 2021 Oct 22. Epub ahead of print. PMID: 34686934.  https://doi.org/10.1007/s10549-021-06418-x. [Link to article]

Find media coverage of the article:

Posted by: Tracy Onega