Cancer research
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A matched case-control study of retinoblastoma was conducted by the Children's Cancer Study Group (CCSG) to investigate the hypotheses that postconception exposures affect the risk of the nonheritable (post-zygotic origin) form of this disease and that preconception exposures affect the risk of the sporadic heritable (prezygotic origin) form. Eligible cases were those patients with retinoblastoma diagnosed in 1982-1985 at any of the CCSG member hospitals. Cases were classified as familial heritable, sporadic heritable, or nonheritable based on family history, tumor laterality, and cytogenetic analysis. ⋯ For the nonheritable group, gestational exposure to X-ray [odds ratio (OR) = 2.3, P = 0.08] and morning sickness medication (OR = 2.8, P = 0.02) and low maternal educational level (OR = 5.5, P = 0.03) were associated with increased risk; anemia (OR = 0.3, P = 0.02) and multivitamin use (OR = 0.4, P = 0.03) during pregnancy and periconceptional use of barrier contraceptive (OR = 0.1, P = 0.02) or spermicide (OR = 0.2, P = 0.02) were associated with decreased risk. In the sporadic heritable group, observations included a negative association with multivitamins during pregnancy (OR = 0.2, P = 0.02) and nonsignificant positive associations with preconception gonadal X-ray (maternal, OR = 2.0, P = 0.30; paternal, OR = 1.8, P = 0.42) and older parental age (case-control difference 1.0-1.2 years, P = 0.24-0.27). Many of the associations support study hypotheses, although the possibility of recall bias and chance findings suggest cautious interpretation.