The risk of developing breast cancer after receiving radiotherapy to the chest as a child are as high as those for BRCA1/2 mutation carriers, according to review of 1,268 cancer survivors and 4,570 female first-degree relatives of participants in the Women’s Environmental Cancer and Radiation Epidemiology (WECARE) Study.1
Breast cancer was diagnosed by age 50 in 24% of all cancer survivors and in 30% of Hodgkin lymphoma survivors. In comparison, among first-degree relatives of the probands, the cumulative incidence by age 50 was 4%; among BRCA1 mutation carriers, it was 31%, and among BRCA2 mutation carriers, the incidence was 10%. Greatly increased risks were observed among women receiving 10 to 19 Gy as well as ≥ 20 Gy.
Approximately 50,000 American women received > 20 Gy as children, and another 7,000 to 9,000 were treated with lower doses, the investigators estimated.
A ‘Sobering’ Finding
At the Best of ASCO Boston meeting, Steven J. Isakoff, MD, PhD, of Massachusetts General Hospital, Boston, commented that the findings were “sobering.”
“Females treated for Hodgkin lymphoma with mantle radiation had a risk of breast cancer that is comparable to carriers of a BRCA1 mutation, and survivors of other childhood cancers treated with chest radiation had a risk comparable to BRCA2 mutation carriers,” he said. “Unfortunately, the study showed that 10 to 19 Gy was associated with the same incidence of cancer. The goal of preventing second malignancies may not be achieved by lowering the dose.”
Guidelines Ignored
The Children’s Oncology Group has recommended that surveillance for breast cancer begin at puberty with breast exams, adding mammography and annual MRI at age 25 or 8 years after radiation therapy, but these guidelines are often ignored. In a 2009 study, almost 50% of childhood cancer survivors younger than age 40 had never had a mammogram,2 he pointed out. Noncompliance with guidelines appears to be due to lack of familiarity of the risk on the part of primary care providers, lack of physician recommendation for screening, and lack of awareness among survivors that they are at increased risk.
Dr. Isakoff posed a provocative question that touches on prevention and protection: “We recommend prophylactic mastectomy for BRCA mutation carriers. Should we be thinking about that in this group as well?” ■
Disclosure: Dr. Isakoff reported no potential conflicts of interest.
References
1. Moskowitz CS, Chou JF, Wolden SL, et al: New insights into the risk of breast cancer in childhood cancer survivors treated with chest radiation: A report from the Childhood Cancer Survivor Study and the Women’s Environmental Cancer and Radiation Epidemiology Study. 2012 ASCO Annual Meeting. Abstract CRA9513. Presented June 4, 2012.
2. Oeffinger KC, Ford JS, Moskowitz CS, et al: Breast cancer surveillance practices among women previously treated with chest radiation for a childhood cancer. JAMA 301:404-414, 2009.
