Low incidence of brain tumors among Ethiopian immigrants in Israel

Studies comparing brain tumor incidence have consistently shown lower incidence in Africans compared to European populations. We compared the incidence of brain tumors in Ethiopian immigrants and their Israel-born descendants with other Israeli subpopulations. We included all cases of benign or malignant brain tumors from 1992 to 2003, as reported to the Israel Cancer Registry, except individuals known to have been irradiated for tinea capitis. Age standardized incidence rates (ASR) and standardized incidence ratios (SIR) were calculated. Among Ethiopian-born immigrants, 38 brain tumors were diagnosed (an ASR of 6.68 per 10⁵ for all brain tumors among Ethiopian immigrants). The incidence of all brain tumors and malignant brain tumors among Ethiopian immigrants was significantly lower than that in Israeli-born Jews [SIR = 0.73, 95% confidence interval (CI) 0.50-0.96, and SIR = 0.65, 95% CI 0.32-0.98, respectively] and in all other Jewish subpopulations. Brain tumor incidence was not significantly different in Israeli-born children of Ethiopian immigrants aged 0-14 compared to Ethiopian immigrants of the same age group (SIR = 0.68, 95% CI 0.14-1.23), and was comparable to incidence among Israeli children of non-Ethiopian parents. We concluded that ethnicity influences brain tumor incidence, and that Ethiopian immigrants to Israel appear to be protected. If an environmental influence on the protective effect of the Ethiopian population in Israel exists, it was not demonstrated in the study in a statistically significant manner. Further investigation is needed to understand the factors involved in the incidence variation among different populations.