Increased breast cancer risk after radiotherapy for acne among women with skin cancer

BackgroundRadiotherapy was commonly used to treat benign conditions, especially skin diseases, during the first half of the twentieth century. Previous studies have shown that radiotherapy for some of these conditions increases the risk of developing breast cancer. Although breast cancer associated with previous radiotherapy for acne has been reported, no statistically significant correlation has been established.ObjectiveThe aim of this study was to determine whether radiotherapy for acne is a risk factor for subsequent development of breast cancer.MethodsA retrospective nested case-control study was conducted using the cohort of all patients referred for Mohs micrographic surgery to the senior author (R. G. B.) from 1978 to 2003. The case group consisted of 244 women who were skin cancer patients and who had received radiotherapy for acne. The control group consisted of 244 age-matched women skin cancer patients from the same records randomly selected within the initial Mohs micrographic surgery treatment year. Clinical data from both groups regarding cancer history and radiotherapy were extracted and statistically analyzed.ResultsWomen skin cancer patients who had received radiotherapy for acne have a prevalence of breast cancer of 15% compared with 6.6% in control women skin cancer patients, for an odds ratio (OR) of 2.5 (P = .0033; 95% confidence interval, 1.3-4.6). Increased prevalence is correlated with age at treatment younger than 20 years (age-adjusted OR, 2.9; age-adjusted P = .002), treatment sessions numbering 5 or more (age-adjusted OR, 3.5; age-adjusted P = .005), and treatment year occurring before 1950 (age-adjusted OR, 2.9; age-adjusted P = .00013).LimitationsThe data used are based primarily on patient history and physical examinations and are therefore limited by the accuracy of the patient and the caregiver.ConclusionWomen with skin cancer exposed to previous radiotherapy for acne are significantly more likely to develop breast cancer than their age-matched controls with skin cancer. Therefore all women previously treated for acne with radiotherapy should be identified and closely monitored for subsequent breast cancer development.