LEW, Rat Strain

**Semantic type:** Mammal

**Definition:** Of the large spectrum of 52 histologically different types of tumors, the highest incidence was observed for adenomas of the pituitary and adenomas/adenocarcinomas of the adrenal cortex in both sexes, mammary gland tumors and endometrial carcinomas (45%) in females, and C-cell adenomas/adenocarcinomas of the thyroid gland and tumors of the hemopoietic system (28%) in males (Baum et al, 1995).