Hormone receptor status/stage and breast cancer patterns in Asian Americans

PL01-04

There is accumulating evidence from epidemiological studies conducted in western populations that breast cancer risk factors vary by hormone receptor status. However, information on risk factor associations by hormone receptor status is sparse in Asians. We conducted a population-based case-control study of breast cancer in Los Angeles County which included 1,277 (450 Chinese, 352 Japanese, 475 Filipinos) women with incident, histologically confirmed breast cancer and 1,160 control subjects (486 Chinese, 311 Japanese, 363 Filipinos). In-person interviews were conducted using a standardized, structured questionnaire that covered demographic characteristics and migration history, menstrual and reproductive factors and use of exogenous hormones, body size, physical activity and diet history. Overall, 16% of case patients had in situ breast cancer while 84% had invasive (54% localized, 30% advanced) breast cancer. Hormone receptor status was abstracted from the pathology records; 91% of the case patients with invasive breast cancer had information on estrogen receptor (ER) while 81% had information on progesterone receptor (PR). In this study of Asian-American women, risk of breast cancer increased significantly in association with nulliparity, low physical activity, high waist to hip ratio, history of diabetes, and low intake of soy foods and green tea. In addition, risk of breast cancer in postmenopausal women was increased in relation to high recent weight and use of menopausal hormones, particularly use of estrogen-progestin therapy (Wu et al., 2007a, Wu et al., 2007b). The impact of these risk factors on breast cancer risk in Asian American women will be presented by hormone receptor status and tumor stage. These results in Asian American women will be compared to those reported on White and African-American women from population-based case-control studies of breast cancer that were conducted using similar study methods (Ursin et al., 2005; Ma et al., 2006).
 References
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 Wu AH, Yu MC, Tseng CC, Pike MC. Diabetes and risk of breast cancer in Asian-American women. Carcinogenesis 28: 1561-1566, 2007b.
 Ursin G, Bernstein L, Lord SJ, Karim R, Deapen D, Press MF, et al. Reproductive factors and subtypes of breast cancer defined by hormone receptor and histology. Br J Cancer 93: 364-371, 2005.
 Ma H, Bernstein L, Ross RK, Ursin G. Hormone-related risk factors for breast cancer in women under age 50 years by estrogen and progesterone receptor status: results from a case-control and a case-case comparison. Breast Cancer Research 8: R39, 2006.