Mammographic density and breast cancer risk by family history in women of white and Asian ancestry
A partir de données de quatre études menées aux Etats-Unis et au Japon (1 699 cas et 2 422 témoins), cette étude analyse l'association entre la densité mammaire, une histoire familiale de cancer du sein et le risque de cancer du sein chez une population blanche ou d'origine asiatique
Purpose : Mammographic density, i.e., the radiographic appearance of the breast, is a strong predictor of breast cancer risk. To determine whether the association of breast density with breast cancer is modified by a first-degree family history of breast cancer (FHBC) in women of white and Asian ancestry, we analyzed data from four case–control studies conducted in the USA and Japan. Methods : The study population included 1,699 breast cancer cases and 2,422 controls, of whom 45 % reported white (N = 1,849) and 40 % Asian (N = 1,633) ancestry. To standardize mammographic density assessment, a single observer re-read all mammograms using one type of interactive thresholding software. Logistic regression was applied to estimate odds ratios (OR) while adjusting for confounders. Results : Overall, 496 (12 %) of participants reported a FHBC, which was significantly associated with breast cancer risk in the adjusted model (OR 1.51; 95 % CI 1.23–1.84). There was a statistically significant interaction on a multiplicative scale between FHBC and continuous percent density (per 10 % density: p = 0.03). The OR per 10 % increase in percent density was higher among women with a FHBC (OR 1.30; 95 % CI 1.13–1.49) than among those without a FHBC (OR 1.14; 1.09–1.20). This pattern was apparent in whites and Asians. The respective ORs were 1.45 (95 % CI 1.17–1.80) versus 1.22 (95 % CI 1.14–1.32) in whites, whereas the values in Asians were only 1.24 (95 % CI 0.97–1.58) versus 1.09 (95 % CI 1.00–1.19). Conclusions : These findings support the hypothesis that women with a FHBC appear to have a higher risk of breast cancer associated with percent mammographic density than women without a FHBC