The likelihood of developing basal cell carcinoma was approximately 40 times higher among participants of the Childhood Cancer Survivor Study (CCSS) who received a dose of 35 Gy or more to the skin from radiation therapy than survivors who were not treated with radiation, according to a study published in the Journal of the National Cancer Institute.1
“This study provides new information on the role of ionizing radiation in the development of [basal cell carcinomas] by defining the dose-dependent relationship between the amount of radiation to the skin and subsequent risk of developing a [basal cell carcinoma],” CCSS researchers stated. They noted that results “were consistent with a linear dose–response relationship, with an excess odds ratio per Gy of 1.09 (95% CI = 0.49–2.64).”
For the study, each of 199 CCSS participants reporting a basal cell carcinoma diagnosis were matched on age and length of follow-up with three participants who did not develop basal cell carcinoma. “The median age at [basal cell carcinoma] diagnosis was 31 years (range, 11–46 years), and 83% of case subjects were diagnosed with their first [basal cell carcinoma] between the ages of 20 and 39 years. The median time from first primary cancer diagnosis to [basal cell carcinoma] diagnosis was 18.2 years (range, 5.2–29.6 years),” the researchers reported.
Multivariate analysis found that radiation therapy was the only treatment-related exposure, but markers of sensitivity to UV radiation, such as light skin and hair color, were also associated with a higher risk of basal cell carcinoma.
“As the survival of those treated for childhood malignancies continues to improve, it is important to understand and educate survivors about treatment-related late effects, such as subsequent malignancies. Fewer than 30% of childhood cancer survivors seek appropriate medical care, either because they are not aware of their initial diagnosis or, more frequently, because they do not know the risks associated with the therapy they received,” the authors concluded.
“An understanding of the radiation dose-dependent nature of [basal cell carcinoma] risk may facilitate the development of improved surveillance and treatment guidelines for physicians who care for cancer survivors,” they added.■
1. Watt TC, Inskip TC, Stratton K, et al: Radiation-related risk of basal cell carcinoma: A Report From the Childhood Cancer Survivor Study. J Natl Cancer Inst 104:1240-1250, 2012.