Women at high risk for breast cancer benefit from both mammography, MRI

Alternating MRI with mammography every six months picks up breast cancers not identified by mammography alone for women at high risk, according to research out of the University of Texas M.D. Anderson Cancer Center in Houston.

Dr. Huong Le-Petross, an assistant professor of radiology at M.D. Anderson, and colleagues presented the findings of their retrospective chart review at the 31st annual San Antonio Breast Cancer Symposium.

The researchers performed their pilot study on 334 consecutive women who were seen at the high-risk clinic from January 1997 to December 2007. Of those patients, 26% (86) underwent annual screening mammography and MRI, alternating every six months. The remaining patients underwent prophylactic mastectomies or were treated with chemoprevention. Clinical exams were performed every six months.

The 86 alternate screening patients had a 20% or higher lifetime risk of developing breast cancer: 70 had BRCA mutations, and 16 had a history of breast cancer or a biopsy of atypia or lobular carcinoma in situ.

Only 6% of the 86 patients completed the fourth round of MRI surveillance. The researchers identified nine cancers in seven women with screening MRI: six invasive ductal, one invasive lobular, and two ductal carcinomas in situ.

Four of these cancers were identified by MRI only, four were identified by both MRI and mammography, and one was not identified by either. Dr. Le-Petross' team found that the mammogram performed six months earlier was normal or demonstrated benign findings for four of the eight MRI-detected cancers.

"The global picture is that MRI can pick up cancers that mammography cannot," Le-Petross said.

Some institutions already use mammography and MRI in tandem as the standard of care.

At the University of North Carolina, Chapel Hill, women at high risk for breast cancer get a mammogram and MRI at the same time once a year, according to Dr. Cherie Kuzmiak, an assistant professor of radiology and director of breast imaging at UNC School of Medicine.

"Part of the reason is a lot of these women who are high risk are younger and are still having their menstrual cycles; they are pre- or perimenopausal. The breast is a living structure -- it's dynamic, not static, so if they have some hormonal changes, you can get false positives. That's why we try to get them all in one fell swoop," she said.

MRI cannot replace mammography nor vice versa, according to Kuzmiak. The tests work in conjunction with one another because mammography is good for finding calcifications while MRI shows blood flow to masses.

One of the limitations of this study is its small numbers, Kuzmiak said.

"This would be a great study for [the American College of Radiology Imaging Network]. Through ACRIN, there are so many academic and private institutions that they can get a lot of numbers quickly," Kuzmiak said.

For more information from the Diagnostic Imaging archives:

Nuclear medicine tackles limits of other screening optionsGenetic testing taps at-risk women for MRI monitoringUltrasound could overcome flaws and play supplemental role in breast screening