The American Cancer Society (ACS) recommends yearly breast cancer screening with both breast MRI (magnetic resonance imaging) and mammography for women with an abnormal breast cancer gene (BRCA1 or BRCA2), as well as for women with a strong family history of breast cancer.
New research published in the Journal of Clinical Oncology has found that women with an abnormal BRCA1 or BRCA2 gene screened with MRI were less likely to be diagnosed with advanced-stage breast cancer compared to being screened with other tests. For women with an abnormal breast cancer gene, MRI screening was better at detecting breast cancer earlier, at a more treatable stage, compared to mammography, ultrasound, or physical exam screening.
Most inherited cases of breast cancer are associated with two abnormal genes: BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two). Women with an abnormal BRCA1 or BRCA2 gene have up to an 85% risk of developing breast cancer by age 70. Their risk of ovarian cancer also is higher than average. Because of their substantially higher risk of breast cancer, more aggressive breast cancer screening makes sense for these women.
In the study, researchers looked at the breast health histories of 1,275 women with an abnormal BRCA1 or BRCA2 gene:
- 445 women had a screening breast MRI every year for 5 years (called the MRI group)
- 830 women had other breast cancer screening tests -- ultrasound, mammograms, and/or physical exams -- but not breast MRI (called the other group)
The researchers then figured out how many women in each group had been diagnosed with either DCIS (ductal carcinoma in situ) or invasive breast cancer during a little more than 3 years of follow-up. DCIS (also referred to as stage 0 breast cancer) is not invasive cancer. DCIS stays inside the breast milk duct.
The proportion of women diagnosed with DCIS or any stage of invasive breast cancer was the same in each group:
- 41 of the 445 (9.2%) women in the MRI group were diagnosed
- 76 of the 830 (9.2%) women in the other group were diagnosed
Diagnosed women in the MRI group were almost twice as likely to be diagnosed with DCIS or stage I invasive breast cancer and 70% less likely to be diagnosed with more advanced invasive breast cancer (stage II, III, or IV):
- 13.8% of the women in the MRI group were diagnosed with DCIS or stage 1 cancer compared to 7.2% of the women in the other group
- 1.9% of the women in the MRI group were diagnosed with stage II, III, or IV invasive breast cancer compared to 6.6% of the women in the other group
The average size of invasive breast cancers (0.9 centimeters or about one-third inch) diagnosed in the MRI group was only half the size of the invasive breast cancers diagnosed in the other group (1.8 centimeters or about two-thirds inch).
These results suggest that MRI screening is better at finding breast cancer at an earlier -- and more treatable -- stage in women with an abnormal breast cancer gene compared to other types of screening. This supports ACS recommendations for screening women with an abnormal gene. Other research reviewed by Breastcancer.org suggests women who have been diagnosed and treated for breast cancer would benefit from yearly screening with BOTH mammography and breast MRI rather than only a yearly mammogram. Read the Opt for MRI in High-Risk Women Research News story.
If you have an abnormal breast cancer gene, are at high risk for breast cancer because of a strong family history, or have a personal history of breast cancer, you and your doctor should develop a screening plan tailored to your specific situation. If the plan doesn't include breast MRI in addition to regular mammograms, you may want to talk to your doctor about the results of this study and ask if breast MRI screening makes sense for you.
You can learn more about mammograms, breast MRIs, and other ways to screen for breast cancer in the Breastcancer.org Screening and Testing section.