MRI for High-Risk Breast Cancer Screening

What is the problem and what is known about it so far?
Women with a family history of breast cancer or with known genetic risk factors (BRCA-1 and BRCA-2 gene mutations) are at increased risk for developing breast cancer. In these women, breast cancer tends to develop before age 50. Mammography is not as reliable for detecting breast tumors in this younger age group compared to older women.

Why did the researchers do this study?
This study was done to investigate the role of MRI (magnetic resonance imaging) in screening high-risk women with a known genetic risk factor for breast cancer. The researchers wanted to determine if MRI would find more tumors than mammography and clinical breast exam, which is currently recommended for screening.

Who was studied?
A total of 1909 Dutch women participated in this study. Women with a lifetime risk of breast cancer exceeding 15% due to genetic factors and aged 25-70 were included.

How was the study done?
All participants were screened with clinical breast exam by a physician every 6 months and a mammogram and MRI each year, from 11/1/99 through 10/1/03. The results were compared with two other groups of women not receiving MRI screening.

What did the researchers find?
During the study 51 breast cancers were detected. MRI detected 32 cancers, whereas 13 were missed. In comparison, mammography only identified 18 cancers and missed 27. Mammography was better at detecting an earlier stage of breast cancer called Ductal Carcinoma In-Situ. Tumors detected in the study group were smaller and less likely to have spread to lymph nodes than those in the comparison groups.

What were the limitations?
The lack of a comparison group screened at the same time as the study group makes it harder to accept the results. This study also provides no information regarding survival benefits from earlier tumor detection.

What are the implications?
MRI is better than mammography in identifying breast cancer in women with known genetic risk factors. MRI contributed to earlier detection of tumors. MRI screening is, however, more expensive than mammography and led to a greater number of unnecessary biopsies of what turned out to be non-cancerous nodules. Its usefulness for screening in the general population over 50 years of age is currently unproven.

Summarized by Rosiane Alfinito, College of Medicine, University of Vermont.
Summarized from "Efficacy of MRI and Mammography for Breast-Cancer Screening in Women with a Familial or Genetic Predisposition." Kriege M, et al., New England Journal of Medicine, July 2004, Volume 351, Number 5, pages 427-437.