Background: Evidence suggests that the presence of Type-2 diabetes at the time of breast cancer diagnosis adversely affects survival independent of breast cancer stage, grade, and tumor phenotype. Few of these epidemiological studies have included Hispanic breast cancer survivors in whom diabetes and obesity are prevalent.

Objective: We examined the association between self-reported diabetes history, breast cancer-specific and all-cause mortality among Hispanic and non-Hispanic white (NHW) women diagnosed with breast cancer (stages I-IIIa) from the New Mexico Health, Eating, Activity, and Lifestyle cohort.

Methods: A total of 399 breast cancer survivors (96 Hispanic, 303 NHW) contributed data for the present study. Women with breast cancer diagnosed between July 1996 and March 1999 were ascertained through the National Cancer Institute's Surveillance Epidemiology and End Results (SEER) registry in New Mexico. Baseline demographic characteristics and breast cancer risk factors were collected approximately 5 months post diagnosis by trained interviewers. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using multivariable Cox proportional hazards regression models. Models were further stratified by ethnicity.

Results: After a median follow-up time of 13.5 years from baseline interview to death, a total of 134 deaths occurred. The prevalence of diabetes did not significantly differ by ethnicity in our study; 11.5% of Hispanics reported having diabetes compared to 7.5% of NHW women. While a history of diabetes was associated with older age at breast cancer diagnosis (p=0.001), higher percent body fat (p=0.01), higher body mass index (p< 0.001), and increased waist-hip ratio (p< 0.001) compared to non-diabetics, no significant differences were observed between diabetics and non-diabetics for breast cancer stage, grade, tumor phenotype, or receipt of breast cancer treatment. In multivariable models, diabetes was associated with increased risk of all-cause mortality overall (HR, 2.10; 95% CI 1.24-3.55), with a significant association only observed among Hispanic women (HR, 3.07; 95% CI 1.05-8.94) when compared to NHW women (HR, 1.66; 95% CI 0.86-3.24). The interaction between ethnicity and diabetes was not statistically significant for all-cause mortality. Diabetes also was significantly associated with increased risk of breast cancer-specific mortality (HR, 2.89; 95% CI 1.27-6.60); however results were not statistically significant by ethnicity.

Conclusions: Overall, diabetes significantly increased risk of all-cause mortality among women diagnosed with invasive BC from our study, particularly among Hispanic women. Diabetes was also found to be a significant prognostic factor for breast-cancer specific mortality. Future studies utilizing this data will be conducted to further evaluate the association between diabetes, glycemic control and breast cancer-specific mortality in Hispanic and NHW women.

Citation Format: Connor AE, Visvanathan K, Boone SD, Baumgartner KB, Baumgartner RN. The association between type-2 diabetes and risk of mortality after invasive breast cancer among Hispanic and non-Hispanic white women from New Mexico [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-10-03.