[Risks factors for pediatric malignant liver tumors]

Pediatric Hepatic Malignancies (PHMs) are the result of the interaction between constitutional and environmental risk factors (RFs). We review the evidence on the main RFs associated to PHMs.

Systematic review of the literature published in the last 25 years on Medline, Embase, Cancerlit, Lilacs and SciElo using the following key words: "etiology/risk factor/epidemiology" and "malignant liver tumors/hepatic cancer" or "hepatoblastoma/hepatocarcionoma".

PHMs account for 1 % of all pediatric malignancies. The main types, hepatoblastoma (HB) and hepatocarcionma (HCC) make up 98-99 % of PHM. The main constitutional RFs are: a) Beckwith-Wiedemann (BW) syndrome; b) isolated hemihyperplasia syndrome (IHS); c) adenomatous polyps of the colon; d) hemochromatosis; e) Hereditary Tyrosinemia Type 1; f) a -1-antitrypsin deficiency; g) porphyrias; h) cirrhosis; i) nonalcoholic steatosis; and j) primary sclerosing cholangitis. The main environmental RFs are: a) hepatitis B virus (HBV) and C virus (HCV); b) B1 aflatoxin (B1AF); c) ionizing radiation; d) alcohol; e) hormonal treatments; f) occupational exposure to pesticides, solvents, vinyl chloride and metals; g) smoking; h) arsenic; i) prematury and very low birth weight; and j) trematodes.

The clinical, analytical and ultrasound screening facilitate the early diagnosis of HB in the previously mentioned genetic syndromes, particularly BW and IHS during the first years of life. HBV universal vaccination of newborns provides the biggest opportunity to prevent a substantial proportion of PHMs. Also systematic monitoring of HBV and HCV in blood, hemoderivates, donated organs and drug addicts, are very useful. Other effective measures are: the reduction/elimination of B(1)AF in food, zero alcohol intake during childhood and adolescence as well decreasing prenatal exposure to the tobacco, solvents, pesticides, vinyl chloride, metals, ionizing radiation and hormonal treatments.