1088 — Post-9/11 deployment history and risk of breast cancer among women Veterans

Lead/Presenter: Allison Gaffey,  COIN - West Haven
All Authors: Gaffey AE (VA Connecticut Healthcare System, Yale School of Medicine), Han L (VA Connecticut Healthcare System, Yale School of Medicine) Ramsey CM (VA Connecticut Healthcare System, Yale School of Medicine) Dziura J (VA Connecticut Healthcare System, Yale School of Medicine) Driscoll MA (VA Connecticut Healthcare System, Yale School of Medicine) Skanderson M (VA Connecticut Healthcare System, Yale School of Medicine) Burg MM (VA Connecticut Healthcare System, Yale School of Medicine) Brandt CA (VA Connecticut Healthcare System, Yale School of Medicine) Bastian LA (VA Connecticut Healthcare System, Yale School of Medicine) Haskell SG (VA Connecticut Healthcare System, Yale School of Medicine)

Objectives:
U.S. military Veterans who served after September 11, 2001 may have unique exposures during deployment. To understand potential health effects of military service that are specific to women, we investigated if post-9/11 women Veterans who deployed would show a greater likelihood of breast cancer than women who did not deploy. Exploratory objectives were to determine if there were age and race differences in the associations between deployment and breast cancer risk, or by healthcare utilization.

Methods:
This retrospective cohort study included all women who were assigned to a primary care provider in Veterans Affairs (VA) medical centers, and received care for at least 180 days after their enrollment, 2001-2021. Because few women deployed post-9/11 and were over age 60, we were not able to make comparisons in this age group. Thus, women aged ?60 years at enrollment were excluded from analyses. Based on VA electronic health records, the exposure of interest was deployment during post-9/11 conflicts and the outcome was a breast cancer diagnosis after entry into VA healthcare. Poisson models were used to evaluate the association between deployment and breast cancer incidence, covarying age, race, ethnicity, alcohol use disorder, smoking, and obesity. A sensitivity analysis was conducted to adjust for healthcare utilization (number of primary care visits in the initial 2 years).

Results:
Of 576,601 women Veterans in VA care, 24.6% (n = 141,935) deployed in support of post-9/11 conflicts. Across follow-up [median (IQR): 8.2 (4.0-13.4) years], 1.2% of women (n = 6935) were diagnosed with breast cancer. Women who deployed were 23% less likely to be diagnosed with breast cancer than their non-deployment counterparts (RR, 0.77, 95% CI: 0.71,0.83). The association remained after including healthcare utilization. In exploratory analyses, deployment by age and deployment by race interaction terms were added to the adjusted model, although neither interaction was significant (ps> 0.05). For further insights, adjusted RR (95% CI) were estimated for deployment exposure by each age and race group, respectively. The effects of deployment on a lower incidence of breast cancer remained significant for women aged 30-39 and 40-49, and those who were White and Black.

Implications:
Despite the exposures that accompany deployment, there was a significantly lower incidence of breast cancer among women who deployed versus not, possibly related to a healthy soldier effect.

Impacts:
There is recent, increased public and political attention to risk for breast cancer among younger women Veterans. As breast cancer is more prevalent among women who served in the military compared to the general population, developing a better understanding of factors that contribute to women Veteran’s risk for breast cancer can help improve risk stratification and the allocation of resources for more timely and cost-effective prevention.