Background: Epidemiologic studies primarily conducted in non-Hispanic white (NHW) women have found that elevated insulin levels, hyperinsulinemia, and chronic hyperglycemia (measured by hemoglobin A1c) are associated with poor prognosis in women diagnosed with breast cancer (BC). Only one study to date has included US Hispanic women, in whom diabetes is highly prevalent.

Objective: We examined the associations between plasma fructosamine, a biomarker of hyperglycemia and glycemic control, self-reported diabetes, and risk of BC-specific and all-cause mortality among Hispanic and NHW women diagnosed with BC (stages I-IIIa) from the New Mexico Health, Eating, Activity, and Lifestyle (HEAL) Study.

Methods: A total of 399 BC survivors (96 Hispanic, 303 NHW) contributed baseline data and plasma samples. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using multivariable Cox proportional hazards regression models. Models were adjusted for age at diagnosis, ethnicity, body size, education, BC stage and treatment.

Results: After a median follow-up time of 13 years from baseline interview to death, a total of 134 deaths occurred, of which 56 deaths were attributed to BC. Approximately 38% of women with diabetes had clinically high fructosamine (> 285 μmol/L). While more Hispanic women had diabetes (11.5%) compared to NHW women (7.6%), significant differences by ethnicity for fructosamine levels were not observed (Hispanic mean= 236 μmol/L; NWH mean=238 μmol/L). Hispanics, however, had larger body size measures at baseline interview compared to NHW survivors. Diabetes was associated with increased BC mortality (HR, 2.89; 95% CI 1.27-6.60) and all-cause mortality (HR, 2.10; 95% CI 1.24-3.55). As a continuous measure, fructosamine was positively associated with BC-specific mortality (p=0.01) and with all-cause mortality, independent of diabetes history (p=0.001). Associations were strongest among women with clinically high fructosamine levels (BC: HR, 4.25; 95% CI 1.67-10.80; all-cause: HR, 2.32; 95% CI 1.30-4.14) compared to women with normal levels (≤285 μmol/L). Significant statistical interactions for associations by ethnicity were not observed.

Conclusions: Our findings suggest that diabetes and fructosamine are significantly associated with increased risk of BC-specific and all-cause mortality among Hispanic and NHW women with invasive BC, even >10 years post diagnosis. Interventions to reduce BC mortality among ethnically diverse BC survivors should also consider methods to improve glycemic control among women with diabetes.

Citation Format: Avonne E. Connor, Kala Visvanathan, Stephanie D. Boone, Kathy B. Baumgartner, Richard N. Baumgartner. The association between diabetes, plasma fructosamine, and risk of mortality after invasive breast cancer among Hispanic and non-Hispanic white women [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C077.