In a retrospective cohort study reported in JAMA Network Open, Stewart et al found that U.S. veterans of the Iraq and Afghanistan wars with moderate/severe or penetrating traumatic brain injury (TBI) were at an increased risk of brain cancer compared to those without TBI.
Study Details
The study used Veterans Affairs and Department of Defense data from October 2004 to September 2019 on veterans from the Long-Term Impact of Military–Relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium. TBI severity was categorized as mild, moderate/severe, or penetrating.
Key Findings
Median follow-up for the cohort was 7.2 years (interquartile range [IQR] = 4.1–10.1) years. After exclusion of 611,107 veterans—primarily due to missing data—1,919,740 veterans were included in the analysis. Most were male (80%) and White (63%). Median age at index date was 31 years (IQR = 25–42 years; index date was date of TBI diagnosis in veterans with TBI and dates simulated by drawing from the distribution of true index dates within each age bracket in those without TBI).
Among the 1,919,740 veterans, 449,880 had TBI, including 385,848 with mild, 46,859 with moderate/severe, and 17,173 with penetrating TBI.
Brain cancer occurred in 318 veterans without TBI (0.02%), 80 with mild TBI (0.02%), 17 with moderate/severe TBI (0.04%), and ≤ 10 (below minimum reportable cell size) with penetrating TBI (≤ 0.06%). Crude incidence rates of brain cancer per 100,000 person-years were 3.06 for no TBI, 2.85 for mild TBI, 4.88 for moderate/severe TBI, and 10.34 for penetrating TBI (overall P < .001).
In analysis adjusted for age, sex, race and ethnicity, service branch, rank, and military component, moderate/severe TBI (adjusted hazard ratio [HR] = 1.90, 95% confidence interval [CI] = 1.16–3.12, P = .01) and penetrating TBI (adjusted HR = 3.33, 95% CI = 1.71–6.49, P < .001), but not mild TBI (adjusted HR = 1.14, 95% CI = 0.88–1.47, P = .31), were significantly associated with subsequent development of brain cancer.
The investigators concluded, “In this cohort study of veterans of the Iraq and Afghanistan wars, moderate/severe TBI and penetrating TBI, but not mild TBI, were associated with the subsequent development of brain cancer.”
Ian J. Stewart, MD, of the Uniformed Services University of Health Sciences, Bethesda, MD, is the corresponding author for the JAMA Network Open article.
Disclosure: The study was supported by the Department of Defense and others. For full disclosures of the study authors, visit jamanetwork.com.
