According to the results of a systematic review published in the April edition of the Annals of Internal Medicine, women treated with therapeutic chest radiation have a substantially elevated risk for breast cancer at a young age that does not appear to plateau.
In the National Cancer Institute-funded review, lead author Tara O. Henderson, MD, of the University of Chicago Pritzker School of Medicine in Chicago, and colleagues sought to assess breast cancer risk and conduct breast cancer surveillance in women following chest radiation for childhood, adolescent or young adult cancer.
Utilizing studies from the MEDLINE, EMBASE, Cochrane Library and CINAHL databases from 1966 to December 2008, three investigators independently extracted data, assessed study quality and selected articles that answered the following questions:
- What is the incidence and excess risk for breast cancer in women after chest radiation for pediatric or young adult cancer?
- For these women, are the clinical characteristics of breast cancer and the outcomes after therapy different from those of women with sporadic breast cancer in the general population?
- What are the potential benefits and harms associated with breast cancer surveillance among women exposed to chest radiation?
The researchers found that standardized breast cancer incidence ratios ranged from 13.3 to 55.5. The cumulative incidence of breast cancer by age 40 to 45 years ranged from 13 to 20 percent and the risk for breast cancer increased linearly with chest radiation dose.
Additionally, Henderson and colleagues noted that while mammography can detect breast cancer, sensitivity is limited.
Citing limitations to their research, the investigators said that the quality of evidence for the second and third aforementioned questions was limited by substantial study heterogeneity, variation in study design and small sample size. However, they wrote that “available limited evidence suggests that the characteristics of breast cancer in these women and the outcomes after diagnosis are similar to those of women in the general population.”
Henderson and colleagues also wrote that further research is required to better define the harms and benefits of lifelong surveillance for breast cancer within this patient population.
“Women treated with therapeutic chest radiation may develop breast cancer,” said Henderson and colleagues. “In this high-risk population, there seems to be a benefit associated with early detection.”