Breast cancer screening with MRI can detect invasive cancers missed by mammography in women who have been treated with radiation therapy to the chest for other conditions, according to a new study published online today in Radiology and slated to appear in print in the magazine’s April issue.
Conducted at Memorial Sloan-Kettering Cancer Center (MSKCC) in New York City, the study reveals that women who as children receive radiation therapy for diseases like Hodgkin's lymphoma are at a significantly higher risk of breast cancer later in life. The incidence of breast cancer increases approximately eight years after chest irradiation, and 13% to 20% of women treated with moderate- to high-dose chest irradiation for a pediatric cancer will be diagnosed with breast cancer by age 40 to 45. In comparison, the researchers found, the cumulative incidence of invasive breast cancer by age 45 among women in the general population stands at 1%.
“MRI's efficacy as an adjunct to mammography in screening women at high risk because of genetic mutation or family history has been established,” said Janice S. Sung, MD, a radiologist at Memorial Sloan-Kettering Cancer Center (MSKCC) in New York City and the study’s lead author. “However, there were no reports in the literature about utility of MRI screening in women who are at high risk specifically due to prior chest irradiation.”
The study involved reviews of screening breast MRIs performed at MSKCC between January 1999 and December 2008 on women with a history of chest irradiation. Sung and her colleagues scrutinized data from 247 screening breast MRIs in 91 women, with a focus on the number of cancers diagnosed, the method of detection, and the tumor characteristics. Four of the 10 cancers identified during the study period were detected with MRI alone; three, with MRI and mammography; and three, solely via mammography. The four cancers detected with MRI alone were invasive, while the three cancers detected with mammography alone were in their early stages.
The addition of MRI to the screening process yielded an incremental cancer detection rate of 4.4%. However, a combination of MRI and mammography produced the highest sensitivity for detecting breast cancers.
"Our results support existing recommendations for annual screening MRI as an adjunct to annual mammography in women with a history of chest irradiation," Sung wrote.
Clear evidence of MRI's benefits notwithstanding, previous research by Sung's colleague and study co-author Kevin Oeffinger, MD, demonstrated that very few women ages 40 to 50 with a history of chest irradiation had undergone screening breast MRI, with lack of awareness and limited insurance coverage the possible reasons, Sung said in a statement."We hope our study and other research will bring more attention to the fact that MRI helps detect more cancers," she added. “We would like to see more high-risk patients undergo screening MRI.”
In addition to Oeffinger, collaborating with Sung on the study were Carol H. Lee, MD, Elizabeth A. Morris, MD, and D. David Dershaw, MD.