INCIDENCE OF INTRACRANIAL TUMORS FOLLOWING HOSPITALIZATION FOR HEAD-INJURIES (DENMARK)

The incidence of brain and other intracranial tumors following head tr auma was evaluated in a cohort of 228,055 Danish residents hospitalize d because of concussion, fractured skull, or other head injury between 1977 and 1992 and followed for an average of eight years (maximum, 17 years). Traffic accidents, falls, and sports-related incidents were t he usual causes of the injury. Malignant and benign neoplasms were ide ntified by linking the study roster with records of the Danish Cancer Registry for the years 1977 to 1993. This approach precludes different ial reporting of injuries by study participants as an explanation for any associations seen. Intracranial tumors of the nervous system occur red more often than expected based on incidence rates for the Danish p opulation; however, most of the excess occurred during the first year after the injury and likely was due to the detection of tumors that we re present before the injury occurred. Excluding the first year of fol low-up, the standardized incidence ratio (SIR) was 1.15 (95 percent co nfidence interval [CI] = 0.99-1.32). The same general temporal pattern was seen for the major subtypes of brain tumor as for all types combi ned. SIRs after the first year were 1.0 for glioma (CI = 0.8-1.2), 1.2 for meningioma (CI = 0.8-1.7), and 0.8 for neurilemmoma (CI = 0.4-1.7 ). However, hemangioblastoma and hemangioma were more frequent than ex pected, based on 15 cases (SIR = 2.6, CI = 1.4-4.2). Results indicate that head trauma causes, at most, a small increase in the overall risk of brain tumors during the ensuing 15 years; however, a possible asso ciation with intracranial vascular tumors warrants further evaluation.