Chemical induction of ovarian tumors in rats

The production and pathogenesis of ovarian cancer was investigated in noninbred albino weanling female rats by surgical fixation into the left ovaries of sutures chemically impregnated with the chemical carcinogens formic acid 2-[4-(5-nitro-2-furyl)-2-thiazolyl]hydrazide (FNT), a nitrofuran antibiotic; N-methyl-N'-nitrosourea (MNU), a direct-acting alkylating agent; or 7,12-dimethylbenz[a]anthracene (DMBA). Rats living more than 30 days following surgery were subjected to complete necropsy of external, thoracic, and abdominal tissues when they died or were killed at 407 days, the study termination. Mean survival of rats in treated and control groups was comparable. All carcinogen-treated rats exposed to FNT, MNU, or DMBA developed one or more ovarian, uterine, or mammary neoplasms with a total of 31 tumors in 22 rats as compared with no tumors in 5 control rats. All carcinogen-treated rats (22) developed ovarian adenomas (18) or adenocarcinomas (4); 3 developed uterine fibroadenomas (1) or squamous cell carcinomas (2); and 6 developed mammary adenocarcinomas. No neoplasms were present in the right ovaries of carcinogen-treated rats. These data suggest that direct application of carcinogens to ovarian tissue is a satisfactory way to develop ovarian adenoma and adenocarcinoma.