Abstract A012: Motherhood and chemotherapy receipt: a population-based study of young women with breast cancer

Abstract Background: Young women, ages 18–39 years, with breast cancer are disproportionately impacted by pronounced socioeconomic disparities, a burden that is exacerbated among mothers as they face competing demands in managing cancer and caregiving responsibilities. Although previous analyses identified 64% of young women with breast cancer as mothers at diagnosis and qualitative studies have reported conflicting views on chemotherapy receipt among mothers, their treatment patterns are not well-defined. Additionally, whether having multiple or young children influences treatment patterns due to increased demands is also unknown. We aimed to determine the association between motherhood or offspring characteristics and chemotherapy receipt by age, stage, race and ethnicity. Methods: We retrospectively linked the Texas Cancer Registry to live birth certificates from 1995 to 2016. Analyses comprised a multicultural, population-based sample of 1,783 mothers who had delivered at least one live birth at diagnosis and 946 young women without children diagnosed with microscopically confirmed invasive breast cancer, between January 1, 2013, and December 31, 2016, at ages 18–39 years. Chemotherapy receipt was based on first course of treatment. Multivariable logistic regression estimated odds ratios (OR) with 95% confidence intervals (CI): model 1 (motherhood), model 2 (number of children), and model 3 (number of young [ages <13 years] children). Model 1 was adjusted for age, stage, insurance, Yost index, receipt of radiation therapy, and surgery type. Models 2 and 3 were adjusted for these covariates plus age of children, number of young children (model 2) and number of children (model 3). Heterogeneity was assessed using single- referent ORs and relative excess risk due to interaction (RERI), and multiplicative models with stratified ORs and likelihood ratio tests (pLRT). Results: Of the 2,729 women, 1,565 (73%) received chemotherapy. There was no association between motherhood (OR=1.00, 95% CI [0.82,1.21]), number of children (OR=0.94, 95% CI [0.72,1.22]), or number of young children (OR =1.07, 95% CI [0.72,1.54]) and chemotherapy receipt. Decreased odds for chemotherapy receipt were observed by race: Non-Hispanic (NH) Black women without children had an ORstratified of 0.57 (95% CI [0.37,0.89]) and NH White mothers had an ORsingle-referent of 0.71 (95% CI [0.51,0.93] and ORstratified of 0.69 (95% CI [0.53,0.95]) compared to NH White women without children (RERI=-0.63, 95% CI [-1.86,-0.09]; pLRT=0.05). Among mothers, those ages >35 years with 2+ young children had an OR of 0.45 (95% CI 0.21,0.98; pLRT=0.39) compared to those with children ages ≥13 years. Conclusion: We found no differences in overall chemotherapy receipt, but observed decreased receipt by race and age, independent of stage, possibly due to unmeasured systemic and clinical factors. Future studies examining detailed tumor characteristics and treatment information could inform targeted interventions to support young women with breast cancer throughout their cancer trajectories. Citation Format: Quiera S Booker, Caitlin C Murphy, Sarah E Messiah, Folefac D. Atem, Bijal S Balasubramanian. Motherhood and chemotherapy receipt: a population-based study of young women with breast cancer [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A012.