Primary and transplantable hepatomas induced by aflatoxin B1 in hypothyroid rats.

The influence of hypothyroidism on AFB1 carcinogenesis in inbred Wistar rats was studied. The primary AFB1 hepatocarcinogenesis was significantly delayed and reduced. The transplantable hepatomas showed prolonged latency periods in rats of both sexes, and in males decreased tumor weights and a lower number of lung metastases were observed. The level of GGTP in serum and liver paralleled the advancement of morphological hepatic lesions, and the activity of serum GGTP in hypothyroid bearers of the transplantable hepatoma was lower in females than in males. It was concluded that the lack of thyroid hormones during the latency period of primary and transplantable hepatomas is decisive for delayed AFB1 carcinogenesis.