Should I get a breast MRI?

I am ask that question often, so lets look into the issue.  The American College of Radiology lists screening criteria at www.acr.org, but begins the list with "current indications for breast MRI include, but are not limited to:"  There is some controversy and a new program of breast MRI accreditation is enrolling now to help sort it out.  I think a breast specialist is needed.  In the meantime lets look at a group, for whom, routine MRI is not in much dispute.

A carrier of a deleterious mutation for breast cancer, BRCA 1 or BRCA 2, has at least an 85% chance of developing breast cancer in her life, much higher than the population risk of 12%.  Fortunately, only about 7% of women are carriers, usually with young primary relatives (mother, daughter, sister) with breast and/or ovarian cancer.  One option for these women is risk reduction TOTAL mastectomy, but the procedure is not chosen by all women who carry one of the gene mutations.  Several reports have been published about MRI in these women with a very high known lifetime risk who have declining surgery.  Let's look at two recent reports, interestingly enough with the same lead author.

Published this week in J Clin Oncol online by Dr. Ellen Warner from Toronto, is a prospective study of 1275 women carriers of the BRCA1 or BRCA2 mutation, comparing routine breast cancer surveillance (Clinical Breast Examination and mammography) without MRI to routine surveillance (CBE and mammography) with added yearly MRI.  The hope is that routine breast MRI would reduce mortality from breast cancer, like routine mammography has done.  When the two groups were compared over time, the number of cancers that developed was the same in each group.  In each group 9.2% of the women were diagnosed with breast cancer in only a mean of 3.2 years of follow-up.  But the tumors in the MRI group were significantly smaller (9mm vs 18mm), more were noninvasive and fewer were later stages.

Breast MRI is more sensitive in finding cancer in these women with a very high lifetime risk of developing cancer, but long term follow-up will be needed to see whether breast cancer mortality is reduced.

The second study in The Breast Journal 2011;17:9-17, by the same author offers more insight into why not offer MRI breast screening to all (lower risk) women.  Even at very experienced breast MRI centers, the false positive rate is too high.  A false positive breast MRI is one that looks like cancer, but isn't, but we don't know until further studies or even breast biopsy have ruled-out cancer.  MRI may be very sensitive at finding cancer, but finds too many benign tumors.  Breast MRI is also much more expensive than other breast screening, even without considering the other procedures, necessary to prove that the positive finding is not breast cancer.

So the answer is, for now, talk to your breast doctor about it.  Breast MRI might be right for you, but in general screening use may cause too much mental and fiscal pain.