Abstract PO-174: Racial and socioeconomic disparities in height and body size in adolescence and risk for breast cancer subtypes in the Young Women’s Health History Study
Authors: Marcus Lydia R. , Pathak Dorothy P. , Hamilton Ann S. , Schwartz Kendra L. , Houang Richard , Sanfelippo Dan A. , Velie Ellen M. 
Published: December 2020

Abstract
The etiology of breast cancer (BC) appears to vary by tumor subtypes and currently, in the United States, non-Hispanic White (NHW) women are at an increased risk for luminal A BC and non-Hispanic-Black (NHB) women are at an increased risk for triple negative (TN) BC. Adolescence is a sensitive time for breast development, and childhood overweight/obesity and short height are associated with lower risk of premenopausal BC. The role of adolescent body size on BC risk by subtype, however, has not been well-studied. Relative to NHW girls and girls with higher socioeconomic position (SEP), NHB girls and those with lower SEP are at increased risk of overweight/obesity throughout life. We examined the association between height and body size in adolescence and odds of BC subtypes and the distribution of these factors by self-reported race and SEP. Data are from the Young Women’s Health History Study, a population-based case-control (case n=1812; control n=1381) study of invasive BC among NHB and NHW women aged 20-49 years. BC was diagnosed in Metro Detroit and Los Angeles County SEER registries, 2010-2015. Tumors were classified as luminal A, luminal B, HER2-type, or TN based on estrogen, progesterone, and HER2 receptor status and tumor grade. Area-based controls were frequency matched to cases on site, race and age. During in-home interviews, participants recalled body size at age 12 years with somatotypes (6 levels), weight at age 18 years (used to calculate body mass index (BMI)), and both measured and recalled adult height (&lt;64, 65-66, &gt;67 inches). Data were also collected on self-reported race, adult SEP (household percent poverty (HHP)), and established BC risk factors to evaluate confounding. Adjusted weighted logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CIs) of BC subtype (vs controls). We also examined potential interactions with race and SEP. Among controls, NHB women and women with lower SEP (&lt;150% HHP) were more likely to report a higher age 12 somatotype (SEP X2 p=0.02; race X2 p=0.08) and age 18 BMI (SEP X2 p&lt;0.01; race X2 p&lt;0.01); height did not vary by race or SEP. For age 12 somatotype a trend for reduced odds with increased somatotype was observed for Luminal B BC (p=0.05) and potentially TN (p=0.08). Women with age 18 BMI &gt;30 vs 18.5-&lt;25 kg/m2 had lower odds of luminal A (OR=0.43, 95% CI 0.22, 0.87); women with age 18 BMI &lt;18.5 vs 18.5-&lt;25 kg/m2 had increased odds of HER2-type BC (OR=1.85, 95% CI 1.03, 3.32). Taller height (&gt;67 vs 65-66 inches), was associated with increased odds of all BC subtypes, most strongly for HER2-type (OR=1.80, 95% CI: 1.07, 3.03) and TN (OR=1.42, 95% CI: 0.98, 2.07) BC. The effect of these three body size measures on BC subtype risk did not vary by race or SEP. Body size in adolescence appears to be associated with risk for some BC subtypes, perhaps through hormonal mechanisms, and may partially contribute to explanations for racial and SEP disparities.
Citation Format: Lydia R. Marcus, Dorothy P. Pathak, Ann S. Hamilton, Kendra L. Schwartz, Richard Houang, Dan A. Sanfelippo, Ellen M. Velie. Racial and socioeconomic disparities in height and body size in adolescence and risk for breast cancer subtypes in the Young Women’s Health History Study [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-174.