Development of unfavorable hepatoblastoma in children of very low birth weight: results of a surgical and pathologic review.

BACKGROUND

The incidence of hepatoblastoma in children of very low birth weight (< 1500 g) is increasing in Japan. The authors reviewed surgical and pathologic aspects of the tumor to clarify the characteristics of the patients.

METHODS

Fifteen patients (9 boys and 6 girls) who were diagnosed between the ages of 6-77 months (median, 16 months) were identified from the data in the Japan Children's Cancer Registry and the data base of medical journals. The patients' birth weights ranged from 560-1380 g (median, 826 g) and the gestational age ranged from 23-33 weeks (median, 25 weeks). The medical records of all patients were reviewed and the patient's stage of disease according to the classification of the Japanese Society of Pediatric Surgeons, treatment, and outcome were analyzed.

RESULTS

Ten tumors (67%) were classified as Stage II or IIIA and 5 (33%) were classified as Stage IIIB or IV. There was a significant correlation between the gestational age and tumor stage (correlation coefficient - 0.6851; P = 0.0048). The gestational age of the 5 patients with Stage IIIB or IV tumors was 23-25 weeks (median, 24 weeks), whereas it was 25-33 weeks (median, 27.5 weeks) for the 10 patients with Stage II or IIIA tumors (P = 0.0036). Birth weight ranged from 560-826 g (median, 734 g) in Stage IIIB and IV patients, which was significantly lower than that in Stage II and IIIA patients (range, 607-1380 g, median, 909 g; P = 0.0500). Complete tumor resection was achieved in 7 patients (47%). The actuarial 2-year survival of all patients was 0.42, and the 2-year survival of patients who underwent complete tumor resection was 0.69, which was significantly better than the 2-year survival of those who underwent incomplete resection (0.17; P = 0.0211). The 2-year survival of the patients with tumors of well differentiated histology was 0.60, which also was significantly better than the 2-year survival of those with tumors of poorly differentiated histology (0.19; P = 0.0453).

CONCLUSIONS

These results indicate that children of very low birth weight (< 1500 g) are at high risk of developing advanced hepatoblastomas and that hepatoblastoma with unfavorable biologic behavior develops in children who are extremely premature at birth. These new findings suggest the presence of etiologic factors relevant to the patient's immaturity and the development of unfavorable hepatoblastoma.