Abstract P3-01-07: ESTIMATED RISK OF RADIATION-INDUCED BREAST CANCER FROM MAMMOGRAPHIC SCREENING

Abstract

Abstract Objective: Estimate the benefit–risk balance of mammography, as number of lives saved/lost in an opportunistic screening in the state of Goiás, Brazil, in 2010, according to type of technology available and age group indicated for screening. Methods: The number of lives saved was estimated considering the gross mortality rate for breast cancer, female population living in the state, estimated mortality rate reduction due to screening programs, and mammographic coverage in the state. For number of lives lost, the model adopted by the Biological Effects of Ionizing Radiation (BEIR VII) was used. Based on the mean glandular tissue dose (Dg), the following parameters were calculated: number of radiation-induced cancer cases with one exposure, with several exposures in screening programs and over the lifetime, number of deaths caused by radiation-induced cancer at a certain age and over the lifetime. Dg of each equipment was estimated according to the European protocol, using the incident air kerma (Ki) at the simulator entrance and the half-value layer (HVL) of the X-ray beam, and table values of coefficients to convert Ki into Dg. Ki and HVL were measured in 100 equipments in operation in the state. A standard breast simulator (5.3 cm thickness and 50% glandular tissue) was used. We considered a biannual mammographic screening with an exam routine composed of a cranio-caudal and a mediolateral oblique view and 40–70 and 50–70-year age groups. Results: The mean Dg was 4.28 (±1.06) and 6.61 (±3.67) for conventional and digital equipments, respectively (p < 0.001). A woman undergoing mammography at the age of 40 in a conventional equipment has a 0.243/100000 probability of radiation-induced cancer at the age of 60, whereas using a digital equipment, the probability is 0.375/100000. The number of cases of radiation-induced breast cancer over the lifetime and consequent deaths followed the differences in the doses employed according to type of technology (p < 0.001). The balance between lives saved and lost was 75.5 (1253.8/16.6) and 166.5 (849.4/5.1) for women screened at 40–70 and 50–70 years, respectively. Conclusions: Screening among 50–70-year-olds, performed biannually using conventional equipments, presented more benefits regarding radiation protection. The number of cases of radiation-induced breast cancer and consequent deaths reproduces the same ratio observed for the difference in the doses between the types of technology. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-01-07.