Risk Factors for Childhood Brain Tumors1

Brain tumors are the second most common cancer in children after leukemia and constitute about 20% of all childhood cancers in the United States (1). The annual incidence is approximately 34 pen million children under 15 years of age. The incidence may be rising; the U.S. National Cancer Institute reported an increase in the period 1973-1988 (1). With a 5-year relative survival rate of approximately 58%, brain tumors account for about 24% of the mortality from childhood cancer. Mortality rates have decreased in recent years (1), due to significant advances in neunosungical and neumodiagnostic techniques and radiation therapy (2). However, children who survive their brain tumor are frequently cognitively impaired (3) or have endocrine deficiencies (4). Inasmuch as childhood brain tumors account for a large fraction of the mortality and morbidity from childhood cancer and of the deleterious late sequelae in survivors, an understanding of etiological factors leading to these tumors is crucial for the early detection of children at high risk and ultimately for prevention. Several recent reviews exist in the literature on risk factors for childhood cancer (5-8), but none deals extensively with childhood brain tumors. The most recent review of risk factors for childhood brain tumors dates back to 1980 (9), and since then many papers have been published. A review of the risk factors for childhood brain tumors may assist in evaluating previous studies and initiating further research. Therefore, we reviewed the epidemiological studies on childhood brain tumors that appeared in the literature from 1974 to March 1992 (10-32). All investigations were case-control studies, and their designs are summarized in Table 1.