Abstract P3-14-08: The influence of metabolic factors, migration, and ethnic disparities on breast cancer risk and treatment

Abstract

Abstract Background: Migrant studies have shown an increase in breast cancer incidence rates among immigrants moving from a breast cancer low-incidence to a high-incidence country. However, 30 years after immigration, it remains equivocal to what degree metabolic factors and ethnic disparities affect breast cancer development and treatment. Methods: Using Cox regression models, we examined the association between ethnicity and breast cancer development, and whether this association varied by pre-diagnostic metabolic profiles among 13 802 women, aged 20-75 years, participating in the population-based Oslo Ethnic Breast Cancer Study. Ethnicity was categorized into: women of Western European descent (reference population) and women of non-western ethnicity (ethnic minority). The ethnic minority women were further subclassified into three groups: 1) South Asian, 2) Middle East and North African, and 3) all other non-western origin women. We defined four pre-diagnostic unfavorable metabolic factors (above median body mass index (>24.6 kg/m2), waist:hip ratio (>0.79), triglyceride:HDL-cholesterol ratio (>0.73), and blood pressure (>96.5 mmHg)), which were combined to define three metabolic profiles: (0-2, 3, and 4 unfavorable metabolic factors). A total of 557 women developed invasive breast cancer during a mean 16.5 years of follow-up. Detailed medical records were obtained. Results: Among women with an unfavorable metabolic profile, South Asian women, compared with Western European women, had a 2.3 times higher breast cancer risk (HR 2.30, 95% CI 1.18-4.49). Furthermore, the ethnic minority women, compared with the Western European women, were suggestively more likely to present with triple-negative breast cancer (OR 2.11, 95% CI 0.97-4.61), and less likely to complete all courses of planned taxane treatment (OR 0.26, 95% CI 0.08-0.82). No differences by ethnicity were observed in physicians’ decisions of planned breast cancer treatment, Conclusions: Our results support that metabolic factors, including body composition, serum lipids and blood pressure, are important when balancing breast cancer prevention and disease management among non-western women migrating from a breast cancer low-incidence to a high-incidence country. However, larger studies are needed. Citation Format: Trygve Lofterød, Hanne Frydenberg, Marit Veierød, Anne Karen Jenum, Jon B Reitan, Erik Wist, Inger Thune. The influence of metabolic factors, migration, and ethnic disparities on breast cancer risk and treatment [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-14-08.