Moderate or severe traumatic brain injury tied to subsequent development of brain cancer in young veterans: JAMA
USA: A cohort study of more than 1.9 million veterans of the Afghanistan and Iraq wars showed that traumatic brain injury (TBI) is associated with the subsequent development of brain cancer. However, mild TBI was not associated with later brain cancer diagnoses. The findings were published online in JAMA Network Open on February 15, 2024.
Primary brain cancer is a relatively rare diagnosis that occurs in 7.02 per 100,000 persons in the US, and the prognosis is poor, with a 5-year survival of 35.7%. The most common brain cancer is glioblastoma, which is responsible for 50.1% of cases. Given the low incidence of this cancer form, the evidence is limited regarding potential risk factors.
To date, epidemiologic work examining the potential association of traumatic brain injury with the subsequent risk of brain cancer is conflicting. Further data may be useful. Considering this, Ian J. Stewart, Department of Medicine, Uniformed Services University of Health Sciences, Bethesda, Maryland, and colleagues aimed to examine whether a history of TBI exposure is associated with the subsequent development of brain cancer.
For this purpose, the research team conducted a retrospective cohort study from 2004 and 2019. The median follow-up for the cohort was 7.2 years. The study included Veterans Affairs (VA) and Department of Defense (DoD) administrative data on 1,919 740 veterans from the Long-Term Impact of Military-Relevant Brain Injury Consortium–Chronic Effects of Neurotrauma Consortium.
The main exposure of interest was traumatic brain injury severity (categorized as mild, moderate or severe [moderate/severe], and penetrating). The outcome of interest was the development of brain cancer.
The study led to the following findings:
· After 611 107 exclusions (predominately for no encounter during the study period), a cohort including 1,919 740 veterans was included, most of whom were male (80.25%). The median age at index date was 31 years.
· The cohort included 449 880 individuals with TBI (mild, 385 848; moderate/severe, 46 859; and penetrating 17 173).
· Brain cancer occurred in 318 individuals without TBI (0.02%), 80 with mild TBI (0.02%), 17 with moderate/severe TBI (0.04%), and 10 or fewer with penetrating TBI (≤0.06%).
· After adjustment, moderate/severe TBI (adjusted hazard ratio [AHR], 1.90) and penetrating TBI (AHR, 3.33), but not mild TBI (AHR, 1.14), were associated with the subsequent development of brain cancer.
"In the cohort study of post-9/11 era veterans, we found that moderate/severe TBI and penetrating TBI were associated with the subsequent development of brain cancer," the researchers wrote.
While there was a small absolute number of brain cancer diagnoses, these diagnoses are tied to profoundly poor outcomes.
"Given that traumatic brain injury is a common injury incurred in the course of military service, further research of this rare but devastating condition is needed to better identify those at risk and develop screening protocols," the research team concluded.
Reference:
Stewart IJ, Howard JT, Poltavskiy E, et al. Traumatic Brain Injury and Subsequent Risk of Brain Cancer in US Veterans of the Iraq and Afghanistan Wars. JAMA Netw Open. 2024;7(2):e2354588. doi:10.1001/jamanetworkopen.2023.54588
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