Comparative Urinary and Gallbladder Carcinogenicity of N-[4-(5-Nitro-2-Furyl)-2-Thiazolyl]Formamide and N-[4-(5-Nitro-2-Furyl)-2-Thiazolyl]Acetamide in the Dog

Summary

N-[4-(5-nitro2-furyl)-2-thiazolyl]formamicle, a urinary bladder carcinogen for the rat and mouse, was fed to 4 female mongrel dogs at a dosage of about 50 mg/kg/day for 2 years followed by 9 months of normal diet. The incidences of tumors observed were: urinary bladder transitional cell carcinoma—4/4; ureteral transitional cell carcinoma—2/4; renal pelvis transitional cell carcinoma—2/4; gallbladder adenocarcinoma—4/4; mammary scirrhous carcinoma—2/4; and mammary fibroadenoma—2/4. A close structural analogue N-[4-(5-nitro-2-furyl)-2-thiazolyl]acetamide, a carcinogen for the breast, salivary gland, lung, and kidney pelvis of the rat and a potent murine leukemogen, was fed to 2 other female mongrel dogs at the same dosage as N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide but for 30 months. The incidences of tumors observed were: gallbladder adenoma—-2/2 and mammary fibroadenoma—2/2. The seemingly minor structural difference of the two compounds significantly altered the distribution and degree of severity of the tumors. No tumors were found in one mongrel female maintained as a negative control.