title: Dose- and time-response for breast cancer risk after radiation therapy for benign breast disease.
abstract: Exposure of the breast to ionising radiation increases the risk of breast cancer, especially among young women. However, some issues remain controversial, for instance the shape of the dose-response curve and the expression of time-related excess. The main purpose of this report was to examine the dose-response curves for radiation-induced breast cancer formulated according to radiobiological target theories. Another purpose was to analyse the time-related excess of breast cancer risk after exposure when dose and age at first exposure were held constant. Breast cancer incidence was analysed in a cohort of 3090 women diagnosed with benign breast disease during 1925-61 (median age 37 years). Of these, 1216 were treated with radiation therapy. The dose range was 0-50 Gy (mean 5.8 Gy). The incidence rate as function of dose was analysed using a linear-quadratic Poisson regression model. Cell-killing effects and other modifying effects were incorporated through additional log-linear terms. Additive and multiplicative models were compared in estimating the time-related excess. The analysis, which was based on 278 breast cancer cases, showed a linear dose-response relationship at low to medium dose levels with a cell-killing effect of 5% Gy-1 (95% confidence interval 2-9%). For a given absorbed dose and age at first exposure the time-related excess was proportional to the background rates with a suggestion that the excess remains throughout life.
authors.affiliation: Oncologic Centre, Karolinska Hospital, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Mattsson
authors.forename: B I
authors.initials: BI
authors.lastname: Rudén
authors.forename: J
authors.initials: J
authors.lastname: Palmgren
authors.forename: L E
authors.initials: LE
authors.lastname: Rutqvist
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001941:Breast Diseases / Q000532:radiotherapy*; D001943:Breast Neoplasms / Q000209:etiology*; D002648:Child; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects; D013997:Time Factors