Chest radiation for Wilms tumor increases breast cancer risk
27 Oct 2014
A new study shows that when a child receives chest radiation for Wilms tumor (a rare childhood cancer), it faces an increased risk of breast cancer later in life. Scientists call for re-evaluation of screening guidelines for breast cancer among Wilms tumor survivors.
About Wilms tumor
Wilms tumor is a rare childhood kidney cancer that can spread to the lungs. When this spread occurs, patients receive a relatively low dose of radiation therapy (12-14 units, or 12-14 Gray) to the entire chest.
Study of 2500 young women: 1 in 5 developed breast cancer by age 40
To see if such exposure to radiation affects patients’ risk of developing breast cancer, Norman Breslow, PhD, of the University of Washington and the Fred Hutchinson Cancer Research Center in Seattle, led a team that studied nearly 2500 young women who had been treated for Wilms tumor during childhood and who had survived until at least 15 years of age.
Of female Wilms tumor survivors who received radiation to the chest, over 20% developed breast cancer by age 40 years (3/4 invasive, 1/4 non-invasive), in contrast to only 0.3% in female Wilms tumor survivors who did not receive radiation.
The researchers also found an intermediate risk (4%) of breast cancer among female Wilms tumor patients who had received abdominal but no chest radiation as part of their treatment for Wilms tumor.
The rates for females receiving chest irradiation, abdominal radiation and no radiation are nearly 30, 6, and 2 times those expected among women of comparable age in the general population.
This high incidence of breast cancer, including invasive cancer, was an unexpected finding.
Guidelines exclude such levels of radiation
“Current guidelines call for early screening for breast cancer among survivors of childhood cancer if they have received 20 or more Gray of radiation therapy to breast tissue. This would exclude a large majority of patients who had received whole chest radiation for Wilms tumor,” said Dr Breslow. “Our results suggest that the risk of early breast cancer among Wilms tumor survivors is sufficiently high that early screening might be considered an option for them also.”
In an accompanying editorial, Jennifer Dean, MD and Jeffrey Dome, MD, PhD of Children’s National Health System in Washington, DC, noted that Wilms tumor survivors at high risk should undergo breast cancer surveillance with mammogram, breast MRI, or both starting at age 25 years.
Need for more risk awareness & surveillance
However, they pointed to research indicating that less than half of childhood cancer survivors considered to have a high risk for breast cancer follow through with surveillance guidelines.
“Because compliance with breast cancer surveillance is low in adult survivors of childhood cancer, barriers such as education of both survivors and providers should be addressed and mitigated,” they wrote.
The corresponding paper was published in "Cancer", a peer-reviewed journal of the American Cancer Society.
Source: eCancer News