Traumatic brain injuries (TBIs) have long been a concern for veterans of the Iraq and Afghanistan wars. These injuries can have significant long-term effects on the physical and mental health of individuals. Recently, a retrospective study has shed light on a potential link between moderate/severe and penetrating TBIs and the development of brain cancer in veterans. The study, conducted by Ian Stewart, MD, and his colleagues at the Uniformed Services University of Health Sciences, analyzed data from 1.9 million veterans and found a statistically significant association between certain types of TBIs and the occurrence of brain cancer.
The Study Findings
In the study, a total of 450,000 veterans reported experiencing TBI. Over a median follow-up period of 7.2 years, the researchers observed brain cancer in 318 veterans without TBI, 80 veterans with mild TBI, 17 veterans with moderate/severe TBI, and 10 or fewer veterans with penetrating TBI. The analysis revealed that brain cancer was associated with moderate/severe TBI and penetrating TBI, but not with mild TBI. The adjusted hazard ratios for brain cancer were 1.90 for moderate/severe TBI and 3.33 for penetrating TBI. These results indicate a higher risk of brain cancer among veterans with more severe TBIs.
The Need for Further Research
The association between TBIs and brain cancer in veterans is a cause for concern and calls for further investigation. As stated by Stewart and his colleagues, brain cancer is a devastating diagnosis with limited known risk factors. With TBIs being a common injury among military personnel, it is crucial to better identify individuals at risk and develop effective screening protocols. Elie Massaad, MD, and Ali Kiapour, PhD, MMSc, from Harvard Medical School, highlighted the importance of identifying contributors to brain cancer in veterans in their accompanying editorial. Glioblastoma, the most aggressive malignant brain tumor, is a leading cause of cancer-related death among active-duty personnel. Post-9/11 veterans have been found to have a 26% higher glioblastoma rate compared to the general public.
Previous studies investigating the link between TBI and subsequent brain cancer have produced mixed results. Some studies have suggested an association between TBI and brain cancer, while others have not observed such a connection. It is important to note that animal studies and research involving stem cells have provided biologically plausible mechanisms that could contribute to this association, including inflammation. However, more definitive research is needed to understand the underlying mechanisms and confirm the findings from this retrospective study.
The Study Methodology
To conduct the study, Stewart and his colleagues analyzed data from the LIMBIC-CENC Phenotypes Study, which consolidates information from Veterans Affairs and Department of Defense sources, as well as the National Death Index. The study included a cohort of 1,919,740 veterans with a median age of 31. The majority of participants were male (80.25%) and white (63.11%). The researchers excluded individuals who developed brain cancer within one year of their TBI to minimize the possibility of reverse causality. They also excluded veterans who had no encounters within the study period.
The findings of this study have significant implications for veterans’ health and the need to prioritize research in this area. It is important to note that the results may not be generalizable to the broader U.S. population as the study focused on a predominantly young, male military population. Additionally, the study did not capture TBIs diagnosed and treated outside of the Veterans Affairs and Department of Defense systems, which may have affected the incidence rates observed. Moreover, potential confounding factors such as toxic exposures were not accounted for, which could impact the results.
The retrospective study conducted by Stewart and his colleagues highlights a potential link between moderate/severe and penetrating TBIs and the development of brain cancer in veterans. The findings emphasize the importance of further research in this field to better understand the underlying mechanisms and develop effective screening protocols. Identifying contributors to brain cancer in veterans is critical for improving their long-term health outcomes. As we work towards providing better care for our veterans, it is important to prioritize research and develop targeted interventions to mitigate the risk of brain cancer associated with TBIs.