Environmental factors for the development of hematopoietic neoplasms in children

Parental age at birth has been investigated in patients diagnosed with pediatric cancer. The Japan Children's Cancer Registry1985-2007 recruited 5,510 patients with leukemia and 8,782 with other cancers. The proportion of patients born to mother and father aged >40 years showed a higher trend in leukemia than that in other cancers (odds ratio [OR] 1.41, p=0.057), especially in 40 years (OR 2.55, p=0.031). We then divided 27,335 patients diagnosed in 1969-2006 into every 8-year birth cohorts to compare proportions of mothers with prenatal medical irradiation. The OR of leukemia was higher than that of other cancers in 1969-1976 (1.25) or 1977-1984 (1.39), which reached statistical significance. We have also studied caregiver's exposure to anticancer drugs. In 15 pediatric patients with cancer who received cyclophosphamide (CPM), the concentration was measured using mothers and medical staff's urine. Five of 7 infants' and 2 of 8 adolescent's mothers showed increased urine CPM levels. CPM was not detected in any medical staff's samples. Maternal exposure to anticancer drugs should also be considered. Efforts of reducing the genotoxicity in both infants and mothers are crucial for pediatric cancer prevention.