Lower Incidence of Breast Cancer Among Female Veterans Deployed During Post-9/11 Conflicts

The incidence of breast cancer was significantly lower in women who deployed in post-9/11 conflicts compared to those who were not, according to findings published in Annals of Epidemiology.

Breast cancer is the most prevalent cancer in female veterans from 20 to 59 years of age. The number of new breast cancer diagnoses in Veterans Affairs (VA) medical centers tripled between 1995 and 2012, likely due to an uptick in the quantity of women treated in VA facilities, said a research team from Connecticut. 

“We hypothesized that women who deployed in support of post-9/11 operations would show a greater incidence of breast cancer,” investigators said.

The retrospective cohort study involved women younger than 60 years of age who were treated at VA facilities from 2001 to 2021. To be enrolled in the study, participants must have been assigned to primary care and received treatment for at least 180 days following their initial visit, researchers said.

Of 576,601 women in the sample, 24% (n=141,935) were deployed during Operations Enduring Freedom/Iraqi Freedom. Findings showed 1.2% of participants (n=6935) were diagnosed with breast cancer with a median follow-up of 8.2 years.

The incidence of breast cancer was 0.034 per 100 person-years among women deployed in post-9/11 conflicts but 0.044 per 100 person-years among women who did not deploy. Women who deployed had a 23% lower likelihood of being diagnosed with breast cancer (95% CI: 0.73, 0.86), according to the findings. Researchers speculated the difference could be due to a healthy soldier effect or screening differences.

“This finding adds to earlier evidence that military deployment per se does not increase women Veterans’ risk of cancer or of disease-related mortality, although past samples were considerably smaller,” investigators concluded.

Reference:
Gaffey AE, Han L, Ramsey CM, et al. Post-9/11 deployment history and the incidence of breast cancer among women veterans. Ann Epidemiol. 2023;77:98-102. doi:10.1016/j.annepidem.2022.11.010