MRI could be key screening component for women at high risk for breast cancer

Annual MRI in combination with mammography can be implemented effectively into organized screening programs for women at high risk for breast cancer, according to study results.

The combined strategy also could be an important management option for women with BRCA mutations, researchers wrote.

In 2011, the Ontario Breast Screening Program (OBSP) began using annual MRI and digital mammography to screen women age 30 to 69 years at high risk for breast cancer.

In the current study, Anna M. Chiarelli, PhD, lead scientist at Cancer Care Ontario, and colleagues evaluated screening results and performance measures from 2,207 women who underwent initial screening exams.

Anna M. Chiarelli

Eligible patients included those with a known mutation in BRCA1, BRCA2 or other gene associated with increased risk for breast cancer; untested first-degree relatives of gene mutation carriers; those with a family history consistent with hereditary breast cancer syndrome and at least a 25% estimated personal lifetime breast cancer risk; and those who underwent radiation therapy to the chest prior to age 30 years and at least 8 years before study entry.

Researchers reported a significantly higher recall rate among women who had an abnormal MRI alone (15.1%; 95% CI, 13.8-16.4) than women who had an abnormal mammogram alone (6.4%; 95% CI, 5.5-7.3) or those who had abnormal mammogram and MRI (4.7%; 95% CI, 3.9-5.5).

Researchers detected 35 breast cancers, equating to an incidence of 16.3 (95% CI, 11.2-22.2) per 1,000 initial screening examinations. Of these, none were detected by mammogram alone, and 23 (65.7%) were detected by MRI alone (incidence, 10.7 per 1,000 initial screening examinations; 95% CI, 6.7-15.8).

Seventy-one percent of breast cancers were detected in women with a known mutation status (incidence, 30.8 per 1,000 initial screening examinations; 95% CI, 19.4-43.7). Detection of breast cancer via mammogram and MRI resulted in the highest positive predictive value (12.4%; 95% CI, 7.3-19.3).

The high cancer detection rate observed with the addition of MRI to mammography show the OBSP’s high-risk screening program is “achieving the expected improved performance,” Chiarelli and colleagues wrote.

“Analysis of the benefits of screening in high-risk women will require consideration of factors other than cancer detection rates alone,” Wendie A. Berg, MD, PhD, FACR, professor of radiology at Magee-Womens Hospital at University of Pittsburgh Medical Center, wrote in an accompanying editorial. “Chiarelli and colleagues did not report further detail of the cancers found only with MRI. Molecular subtype and node status will be important to know for invasive cancers, and additional analyses are planned. … In the interim, women should be informed of the risks of additional testing and biopsy that may not show cancer as a result of supplemental screening MRI.”

For more information:

Berg WA. J Clin Oncol. 2014;doi:10.1200/JCO.2014.56.2975.
Chiarelli AM. J Clin Oncol. 2014;doi:10.1200/JCO.2013.52.8331.

Disclosure: The researchers report no relevant financial disclosures.