Increased incidence rates but no space–time clustering of childhood astrocytoma in Sweden, 1973–1992

Autor: Hjalmars, Ulf, Kulldorff, Martin, Wahlqvist, Yngve, Lannering, Birgitta
Zdroj: Cancer; 1 May 1999, Vol. 85 Issue: 9 p2077-2090, 14p
Abstrakt: Incidence patterns, trends, and spatial and/or temporal clustering of childhood brain tumors were analyzed in the population-based national cancer registry of Sweden. Temporal trends were analyzed by a logistic regression procedure in which the average annual percentages of change in incidence rates and the corresponding 95% confidence intervals (CIs) were calculated. Spatial and/or temporal clustering were investigated by using a geographic information system and analyzed with a modified version of the Knox test and a spatial scan statistic. Primary brain tumors in 1223 children ages 0–15 years were registered during 1973–1992. In 80% of cases, the tumor was classified as malignant. Conclusive histopathology was classified in 1142 cases. The age-adjusted incidence rate for all subtypes of brain tumors was 35.9 cases per million children, and for malignant brain tumors 28.6. A statistically significant increasing temporal trend was observed for the group of malignant brain tumors as a whole (P = 0.0001) and the astrocytoma subgroup (P = 0.0001). The annual average increases were 2.6% (95% CI = 1.5–3.8) and 3.0%, respectively (95% CI = 1.6–4.4). The increase in astrocytoma cases was significantly larger for girls than for boys (P = 0.021) and was most striking for girls ages 6–15 years, with an annual average increase of 4.7%. Rates had not increased for the primitive neuroectodermal tumor (PNET)/medulloblastoma or ependymoma subgroups. The geographic distribution of astrocytoma cases was homogenous. No statistically significant space–time interaction or local clusters in space and/or time were found for astrocytomas only or when astrocytomas were grouped with PNETs/medulloblastomas and ependymomas. The results show statistically increased incidence rates of childhood astroglial tumors, predominantly for girls, in Sweden during the period 1973–1992, but no clustering in space or time. Cancer 1999;85:2077–90. © 1999 American Cancer Society.
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