Can Placenta Factors Explain Race Patterns of Breast Cancer?
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: Asian and Hispanic women experience a striking, reduced incidence of breast cancer in California compared to either Caucasian or African American women. African American women also experience higher rates of mortality and later stage at diagnosis. Understanding race/ethnicity differences in breast cancer incidence offers promise for primary breast cancer prevention and breast cancer mortality reduction for all women. To date, Asian and Hispanic origin, and the novel protective placental factors we described for whites in a recent publication are among the largest protective factors identified. It is critical to understand how they are related.
 
 
 
 
 
 
 
 As for breast cancer, there are striking differences in pregnancy outcomes by race and ethnicity including birth weight. Higher birth weights have reportedly increased breast cancer risk, and birth weights of mothers and daughters are also highly correlated. A key to progress in breast cancer prevention will lie in reconciling critical paradoxes. Race/ethnicity patterns for birth weight (lowest for African Americans and Asians, higher for Hispanics and non-Hispanic whites) do not match patterns of breast cancer in California (lowest in Asians and Hispanics).
 
 
 
 
 
 
 
 There are three aims for this project:
 
 
 
 
 
 
 
 Aim #1 - Test the hypothesis that race/ethnicity differences in the distribution of novel protective placental factors are consistent with patterns of breast cancer incidence in California: 
 
 
 
 Lower incidence for Asians and Hispanics than for whites and African Americans 
 
 
 
 Higher incidence at younger ages among African Americans compared to whites.
 
 
 
 
 
 
 
 Aim # 2 - Test the hypothesis that novel protective placental factors for maternal breast cancer, identified for White women, have similar protective associations for African American women.
 
 
 
 
 
 
 
 Aim #3 - Test the hypothesis that black/white differences in protective placental factors explain later stage at diagnosis among African Americans. 
 
 
 
 
 
 
 
 We propose to carry out these aims by analysis of existing data from a unique California population study, The Child Health and Development Studies, in which fifteen thousand women participated during their pregnancies between 1959 and 1967. At that time, extensive data were collected on the progress of their pregnancies, including standardized examination of the placentas from their pregnancies. They have been followed for breast cancer using the California Cancer Registry. This is one of the only resources in the United States to examine detailed characteristics of pregnancy recorded decades before cancer developed. We will compare characteristics that relate to the placenta, the organ that regulates the baby's growth and the production of hormones responsible for profound changes in pregnancy, for Asian (Chinese, Japanese, and Korean descent), Hispanic, African American, and non-Hispanic white women to determine whether differences in placental function could explain race ethnicity differences in cancer incidence. For African Americans where sample size is sufficient, we will examine whether protective placental factors are less common and explain larger tumor size and poorer prognosis at diagnosis.
 
 
 
 
 
 
 
 In very recent work, we identified placental factors (lower placental weight and diameter, higher increases in blood pressure, and the presence of an abnormal placental condition called maternal floor infarction) during pregnancy as strong protective factors for breast cancer 40 years later. These risk factors are newly described and have never been studied in African Americans (because sample sizes were not large enough until now, as cancer cases have accumulated in our study population over the last 5 years). Nor have the distributions of these risk factors been described for Asians and Hispanics. An editorial that accompanied our publication suggested that uncovering underlying biological factors that explain the protective relations we observed could lead to prevention strategies. Demonstrating race and ethnicity differences in these factors will provide further clues. For example, there is a possibility that tumor suppressor genes have relevance both to the growth of the placenta (which is like a tumor) as well as to breast cancer, and that these genes vary by race/ethnicity.