ESOPHAGEAL-CARCINOMA IN-HOUSE MUSK SHREWS, SUNCUS-MURINUS (INSECTIVORA), INDUCED BY N-METHYL-N'-NITRO-N-NITROSOGUANIDINE

Female 6-week-old shrews were given a solution of N-methyl-N'-nitro-N- nitrosoguanidine (MNNG) at a concentration of 50 mug/ml or 100 mug/ml in the drinking water. All 11 shrews receiving 100 mug/ml MNNG died 8- 13 days after the beginning of carcinogen administration and 6 of the 20 shrews receiving 50 mug/ml MNNG died after 10-54 days. When animals were between 43 and 54 weeks of age, multiple esophageal lesions were evoked in all 14 that had received 50 mug/ml MNNG for 30 weeks. All s hrews developed a protruding, ulcerative, or superficial type of squam ous-cell carcinoma of the esophagus, accompanied by papillomas. Local invasion was seen in squamous-cell carcinoma but no distant metastasis was noted. None of the 5 control shrews developed any esophageal abno rmality. No gastric adenocarcinoma, intestinal sarcoma, or other tumor s were induced with MNNG. It can be concluded that MNNG has a carcinog enic effect on shrew esophageal epithelium.