Chest radiation exposure in youth linked to future breast cancer risk
MedWire News: Women treated with chest radiation for pediatric or young adult cancer have a substantially elevated risk for breast cancer at a young age, which does not seem to plateau, results of a systematic literature review have shown.
Kevin Oeffinger (Memorial Sloan-Kettering Cancer Center, New York, USA) and colleagues reviewed studies published between 1966 and 2008 of girls and women with pediatric or young adult cancer (aged 30 years or younger at diagnosis) who were exposed to moderate to high doses of therapeutic chest radiation.
They aimed to determine the incidence and excess risk for breast cancer in these women, determine whether the clinical characteristics of breast cancer and the outcomes after therapy differ from those of women with sporadic breast cancer in the general population, and assess the potential benefits and harms associated with breast cancer surveillance among women exposed to chest radiation.
The researchers found that there was a significantly increased incidence of breast cancer, absolute excess risk for breast cancer, or both, in association with chest radiation. The standardized incidence ratio ranged from 13.3 to 55.5 and the cumulative incidence of breast cancer by age 40 to 45 years ranged from 13% to 20%.
The increased risk for breast cancer was found as early as 8 years after chest radiation and did not plateau with increasing length of follow-up. In addition, breast cancer risk increased linearly with chest radiation dose.
The evidence suggested that, in this group of women, the characteristics of breast cancer and the outcomes after diagnosis are similar to those of women in the general population.
Oeffinger and team also found mammography can detect breast cancer in these women, but is limited by the high proportion of women (approximately 60%) with moderate to very dense breast tissue.
Of note, the quality of evidence in some reports was limited by substantial study heterogeneity, variation in study design, and small sample size.
In this high-risk population, there seems to be a benefit associated with early detection but further research is required to better define the harms and benefits of lifelong surveillance, conclude Oeffinger et al in the Annals of Internal Medicine.
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By Laura Dean