TY - JOUR
T1 - Birth order and risk of childhood cancer
T2 - A pooled analysis from five US States
AU - Von Behren, Julie
AU - Spector, Logan G.
AU - Mueller, Beth A.
AU - Carozza, Susan E.
AU - Chow, Eric J.
AU - Fox, Erin E.
AU - Horel, Scott
AU - Johnson, Kimberly J.
AU - McLaughlin, Colleen
AU - Puumala, Susan E.
AU - Ross, Julie A.
AU - Reynolds, Peggy
PY - 2011/6/1
Y1 - 2011/6/1
N2 - The causes of childhood cancers are largely unknown. Birth order has been used as a proxy for prenatal and postnatal exposures, such as frequency of infections and in utero hormone exposures. We investigated the association between birth order and childhood cancers in a pooled case-control dataset. The subjects were drawn from population-based registries of cancers and births in California, Minnesota, New York, Texas and Washington. We included 17,672 cases <15 years of age who were diagnosed from 1980 to 2004 and 57,966 randomly selected controls born 1970-2004, excluding children with Down syndrome. We calculated odds ratios and 95% confidence intervals using logistic regression, adjusted for sex, birth year, maternal race, maternal age, multiple birth, gestational age and birth weight. Overall, we found an inverse relationship between childhood cancer risk and birth order. For children in the fourth or higher birth order category compared to first-born children, the adjusted OR was 0.87 (95% CI: 0.81, 0.93) for all cancers combined. When we examined risks by cancer type, a decreasing risk with increasing birth order was seen in the central nervous system tumors, neuroblastoma, bilateral retinoblastoma, Wilms tumor and rhabdomyosarcoma. We observed increased risks with increasing birth order for acute myeloid leukemia but a slight decrease in risk for acute lymphoid leukemia. These risk estimates were based on a very large sample size, which allowed us to examine rare cancer types with greater statistical power than in most previous studies, however the biologic mechanisms remain to be elucidated.
AB - The causes of childhood cancers are largely unknown. Birth order has been used as a proxy for prenatal and postnatal exposures, such as frequency of infections and in utero hormone exposures. We investigated the association between birth order and childhood cancers in a pooled case-control dataset. The subjects were drawn from population-based registries of cancers and births in California, Minnesota, New York, Texas and Washington. We included 17,672 cases <15 years of age who were diagnosed from 1980 to 2004 and 57,966 randomly selected controls born 1970-2004, excluding children with Down syndrome. We calculated odds ratios and 95% confidence intervals using logistic regression, adjusted for sex, birth year, maternal race, maternal age, multiple birth, gestational age and birth weight. Overall, we found an inverse relationship between childhood cancer risk and birth order. For children in the fourth or higher birth order category compared to first-born children, the adjusted OR was 0.87 (95% CI: 0.81, 0.93) for all cancers combined. When we examined risks by cancer type, a decreasing risk with increasing birth order was seen in the central nervous system tumors, neuroblastoma, bilateral retinoblastoma, Wilms tumor and rhabdomyosarcoma. We observed increased risks with increasing birth order for acute myeloid leukemia but a slight decrease in risk for acute lymphoid leukemia. These risk estimates were based on a very large sample size, which allowed us to examine rare cancer types with greater statistical power than in most previous studies, however the biologic mechanisms remain to be elucidated.
KW - birth order
KW - case-control studies
KW - child
KW - epidemiology
KW - neoplasms
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U2 - 10.1002/ijc.25593
DO - 10.1002/ijc.25593
M3 - Article
C2 - 20715170
AN - SCOPUS:79953326185
SN - 0020-7136
VL - 128
SP - 2709
EP - 2716
JO - International Journal of Cancer
JF - International Journal of Cancer
IS - 11
ER -