Research Reports - The long-term risk of malignant astrocytic tumors after structural brain injury
Neuro Oncol. 2014 Nov 21
Munch TN(1), Gørtz S(1), Wohlfahrt J(1), Melbye M(1)
BACKGROUND: Neoplastic transformation of damaged astrocytes has been proposed as
a possible pathological mechanism behind malignant astrocytic tumors. This study
investigated the association between structural brain injuries causing reactive
astrogliosis and long-term risk for malignant astrocytic tumors.
METHODS: The cohort consisted of all individuals living in Denmark between 1978
and 2011. The personal identification number assigned to all individuals allowed
retrieval of diagnoses of traumatic brain injury, cerebral ischemic infarction,
and intracerebral hemorrhage from the National Patient Discharge Register.
Diagnoses of anaplastic astrocytoma and glioblastoma multiforme (World Health
Organization grades III and IV) were retrieved from the Danish Cancer Registry.
Rate ratios (RR's) were estimated using log-linear Poisson regression.
RESULTS: In a cohort of 8.2 million individuals, 404 812 experienced a structural
brain injury and 6152 developed a malignant astrocytic tumor. No significant
association was observed 1-4 years after a structural brain injury (RR = 1.14;
95% CI: 0.87-1.46), whereas the long-term (5+ y) risk for malignant astrocytic
tumors was significantly reduced (RR = 0.68; 95% CI: 0.49-0.90) compared with no
injury. The specific long-term risks by type of injury were: traumatic brain
injury RR = 0.32 (95% CI: 0.10-0.75); cerebral ischemic infarction RR = 0.69 (95%
CI: 0.47-0.96); and intracerebral hemorrhage RR = 1.39 (95% CI: 0.64-2.60).
CONCLUSION: We found no evidence for an association between structural brain
injury and malignant astrocytic tumors within the first 5 years of follow-up.
However, our study indicated a protective effect of astrogliosis-causing injuries
5 or more years after structural brain injury.