Abstract
A38
Background: The majority of studies have reported risks of breast cancer from benign breast disease (BBD) mainly in homogenous Caucasian populations. Information on breast cancer risk factors in larger, multi-ethnic populations would facilitate the development of appropriate and targeted risk reduction strategies. Methods: This nested case-control (1:3 match) study design of 872 women comprised 218 cases of breast cancer (BC). Cases and controls were drawn from a parent BBD cohort of 4,970 women, 1,341 African Americans (AA) and 3,629 non-AA who were diagnosed with BBD after examination of an excisional breast biopsy. Risk factors (34 variables) included demographics, lesion types, and epidemiological variables collected from risk factor questionnaires and medical record charts. Results: Seven individual variables by race interactions (p<0.10) included age, hormone replacement therapy, menopausal status, fibrosis, squamous metaplasia, ADH, and phyllodes tumor. Additionally, nine variables, occupational history, menopausal status, cysts, fibroadenoma, ALH, papilloma, hyperplasia without atypia, lesion risk level (p<0.05), and simple apocrine metaplasia (p<0.10) were included in the initial multivariable model. The final multivariable model (p<0.05) retained lesion risk level, fibroadenoma, and the interaction of age category by race. Women with proliferative lesions (no atypia, risk level 2) were 1.7 times more likely to develop BC as compared to patients with non-proliferative lesions (reference, 95% CI: 1.13, 2.42; p=0.009). Patients with atypia (risk level 3) were 3.75 times more likely to develop BC compared to patients with non-proliferative lesions (95% CI: 1.99, 7.06; p<.001). The presence of fibroadenoma was protective of breast cancer. The odds of breast cancer was approximately 35% lower among patients with fibroadenoma as compared to women without fibroadenoma (OR: 0.65; 95% CI: 0.46, 0.94; p=0.020). The interaction between race and age also was significant, after adjusting for lesion risk level and presence of fibroadenoma. African American patients who were 50 years or older were 2.28 times more likely to develop breast cancer as compared to non African American patients who were less than 50 years old (OR:2.28; 95% CI: 1.34, 3.88; p=0.002). Conclusion: Women with fibroadenoma were less likely to progress to BC, irrespective of whether the fibroadenoma lesion was non-proliferative or proliferative. The interaction between race and age indicated African American patients 50 years and older were 2.28 times more likely to develop breast cancer than non-African American women with BBD who were less than 50 years old. Support: NIH CA 70923 (MJW), ACS EDT-116(MJW)
First AACR International Conference on the Science of Cancer Health Disparities-- Nov 27-30, 2007; Atlanta, GA