methylthiouracil and Lung-Neoplasms

Seventy-five female Wistar rats of 150 g each were given 3 X 40 mg/kg body weight nitrosomethylurea (NMU) and 4 weeks later until death (in the 9th-60th week) methylthiouracil (MTU), as a 0.1% solution in their drinking water. After 2 months, in the almost colloid-less thyroid gland individual foci appeared which consisted of sometimes colloid containing follicles with increased cytoplasmic and nuclear basophilia; they increased in number during the subsequent weeks and finally resulted in nodes with different morphologic structures. From the 16th week on there were tumors infiltrating the capsule, and after the 24th week there were angioinvasive carcinomas. Thirteen rats had developed lung metastasization after the 30th week. Cytology could only distinguish between the follicular carcinomas of low differentiation and the follicular adenomas. If these findings are applied to human pathology, one would have to reckon with adenomas which can develop their malignant characteristics without necessarily changing their histologic and cytologic appearance.

Topics: Animals; Female; Lung; Lung Neoplasms; Methylnitrosourea; Methylthiouracil; Neoplasms, Experimental; Nitrosourea Compounds; Rats; Thyroid Gland; Thyroid Neoplasms

The nature of tumors appearing in the thyroid gland and in the lungs of mice fed two standard goitrogenic drugs (MTU and MII) has been studied. These tumors have been considered malignant on the basis of their morphological appearance and their occurrence in abnormal locations. Some investigatiors, however, have questioned that they are actually malignant. The present results indicate that these tumors are most likely not malignant even if it is shown that the pulmonary nodules are of thyroid origin. The thyroid adenomas disappear once the goitrogen is withdrawn, but thryoid enlargement pesists, and event 6 months after discontinuation of the goitrogenic treatment , pulmonary nodules are still produced. Evidence is presented that these nodules are emoli from hyperplastic thyroid tissue and not tumors.

Topics: Adenoma; Animals; Carcinoma, Hepatocellular; Diet; Glycolysis; Hyperplasia; Iodine; Liver Neoplasms; Lung Neoplasms; Male; Methimazole; Methylthiouracil; Mice; Mice, Inbred Strains; Oxygen Consumption; Thyroid Gland; Thyroid Neoplasms

Topics: Animals; Drug Interactions; Female; Hyperplasia; Isoniazid; Lung Neoplasms; Male; Methylthiouracil; Mice; Mice, Inbred CBA; Mice, Inbred Strains; Neoplasms, Experimental; Thyroid Diseases

Topics: Adenoma; Animals; Body Weight; Cricetinae; Cystadenoma; Female; Iodine Isotopes; Lung Neoplasms; Methylthiouracil; Neoplasms, Experimental; Organ Size; Thyroid Neoplasms