[The tumor spectrum of Him:OFA rats]

The longevity and incidence of spontaneous tumors was investigated in 92 male and 182 female rats of the Sprague-Dawley (SD) derived stock Him: OFA. The overall tumour incidence was 85.9% in males and 97.8% in females with 32 different types of tumors in males and 30 in females. The most frequent neoplasms were mammary tumours in females with 84.6% incidence, followed in this sex by adrenal (36.8%), pituitary (32.9%) and thyroid neoplasms (10.9%). The incidence of all neoplasms in female genital tract was 12.6%. In male rats tumours of the adrenals have the highest incidence (53.2%, most of them cortical) followed by pituitary tumours (31.5%) and neoplasm of the mesenteric lymph nodes (14.1%, which is uncommonly high compared with other Sprague-Dawley stocks). All other tumours are below 10% incidence. The mean lifespan of females is with 719 +/- 142 d shorter than that of males with 752 +/- 108 d because of the high incidence of mammary tumours between 16 to 18 months of age.