MRI Screening for Breast Cancer Recommended for Women with History of Radiotherapy

Breast cancer screening with magnetic resonance imaging (MRI) can detect invasive tumors missed on mammography in women who have undergone chest irradiation for other diseases, according to new findings.

Women who receive radiation therapy as children and young adults for diseases such as Hodgkin's lymphoma face a considerably greater 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 cumulative incidence of invasive breast cancer by age 45 among women in the general population is only 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 the study's lead author Janice S. Sung, MD, a radiologist at Memorial Sloan-Kettering Cancer Center (MSKCC; New York, NY, USA). "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.”

In the study, Dr. Sung and colleagues reviewed screening breast MRI scans performed at MSKCC between January 1999 and December 2008 on women with a history of chest irradiation. They examined data from 247 screening breast MRI scans in 91 women, with an emphasis on the number of cancers diagnosed, the method of detection, and the tumor characteristics.

Of the 10 tumors found during the study period, four were detected with MRI alone, three with MRI and mammography, and three with mammography alone. The four cancers detected with MRI alone were invasive, whereas the three tumors detected with mammography alone were in their early stages.

The addition of MRI to the screening process resulted in a 4.4% incremental cancer detection rate. 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,” Dr. Sung said.

In spite of distinct evidence of MRI's benefits, earlier studies by Dr. Sung's colleague and coauthor Kevin Oeffinger, MD, revealed that very few women ages 40 to 50 with a history of chest irradiation had undergone breast MRI scanning. Lack of awareness and limited insurance coverage are possible reasons, according to Dr. Sung. MRI is considerably more expensive than mammography.

The study's findings were published online and in the April 2011 print edition of the journal Radiology.

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Memorial Sloan-Kettering Cancer Center