Birth weight and other prenatal factors and risk of breast cancer in Asian-Americans

Abstract

Little is known about the role of birth weight and other prenatal factors in the etiology of breast cancer in Asian-Americans. We investigated the relation between birth weight and other prenatal factors and breast cancer risk in a population-based case-control study in Los Angeles County that included 2,259 Asian American women with incident, histologically confirmed breast cancer and 2,019 control women, who were frequency matched to cases on age, Asian ethnicity and neighborhood of residence. Breast cancer risk nearly doubled (odds ratio (OR)=1.92, 95% confidence interval (CI)=1.12-3.29) among those with high (≥4000 g) birth weight compared to those with low (<2500 g) birth weight after adjusting for age at menarche, parity, adult weight and other covariates. Risk increased 8% per 500 g increase in birth weight (p trend=0.10). We observed a significant relationship between birth weight and age at menarche in both cases and controls. Mean birth weight was higher (2948 g) for control women who had early menarche (age ≤11 years) compared to those who had menarche late (age ≥15 years) (2807 g) (P trend =0.016); results were similar among case patients (P trend=0.022). Older maternal age was also a risk factor; risk increased by 6% (95% CI=1.01-1.12) per 5 years increase in maternal age with adjustment for parity and other risk factors. Our results support the hypothesis that high birth weight and older maternal age at pregnancy may have contributed to the rising breast cancer incidence in Asian Americans.

Recognizing the limitations of a meta-analysis

“…They found that non-Hispanic black girls entered menarche at a significantly younger age than their nonHispanic white counterparts. Other investigators have reported similar findings in Asian women, with as many as 24.5% of Japanese women, 16.8% of Filipino women, and 12.3% of Chinese women entering puberty at %11 years of age (2). However, none of the primary studies included in this meta-analysis consider race to be an important variable and therefore the influence of race on age of menarche could not be evaluated at the level of the individual study.…”

Traditional Breast Cancer Risk Factors in Filipina Americans Compared with Chinese and Japanese Americans in Los Angeles County

“…The study population and methods used in this population-based case-control study have been described previously (6, 7). In brief, breast cancer patients were identified by the LA County Cancer Surveillance Program, the population-based cancer registry covering LA County, a member of the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) program, and the statewide California Cancer Registry.…”

Alcohol and breast cancer risk among Asian-American women in Los Angeles County

“…The relation between birth weight and breast cancer risk has been reported in all participants [5]. The study was approved by the Institutional Review Board of the Keck School of Medicine at the University of Southern California.…”