Increased risk of hepatoblastoma among immature children with a lower birth weight.

Hepatoblastomas among children with very low birth weights have significantly increased recently, according to the data from the Japan Children's Cancer Registry for the years 1985-1993. We then analyzed more Registry data for 1969-1994 to clarify the possible relationship between low birth weight and hepatoblastoma. The percentage of low birth weights was compared between 543 hepatoblastoma children in the Registry and all live births in Japan in four successive periods during the 26 years from 1969 to 1994, in relation to the given birth year. The percentage of children with birth weights of 1500-1999 g among hepatoblastomas was higher, at 2.94-1.60%, than that among all live births in each of the four periods (0.79-0.92%), and the percentage of children with birth weights of 2000-2499 g was slightly higher. The percentage of children with birth weights of <1500 g and, especially, <1000 g, has increased rapidly among children born after 1988 (1.60 and 6.40%, respectively), when most very low birth weight infants began to survive. Compared with children with a birth weight of 2500 g or more, the relative risks of hepatoblastoma among children with birth weights of <1000, 1000-1499, 1500-1999, and 2000-2499 g were 15.64 (P < 0.001), 2.53 (P = 0.129), 2.71 (P = 0.001), and 1.21 (P = 0.381), respectively, suggesting the lower the birth weight, the higher the risk of hepatoblastoma. There was no association between hepatoblastomas with a low birth weight and either age at diagnosis or congenital malformations or light-for-date weight. The risk of hepatoblastoma for low birth weight children may be inherently high, especially for lower birth weights, and the recent rapid increase may be a result of an increase in the number of more immature infants with a more sensitive liver and also more frequent exposure to risk factors related to perinatal treatment.