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Feeding N,N'-2,7-fluorenylenebisacetamide (CAS:304-28-9) at 0.025% to 15 male and 15 female mastomys considerably shortened their life-span. At death every treated mastomys had several primary tumors; untreated animals at comparable ages had none. Several mastomys with hepatoblastomas and 1 with giant cell hepatitis and a metastasizing pancreatic carcinoma are first reported here. The tumor load per animal averaged 4.0 for treated females, 2.6 for treated males, 1.5 for untreated females, and 0.6 for untreated males. Of 24 hepatic tumors in treated mastomys, 11 metastasized, compared to none of the incipient tumors in 8 of 26 untreated animals. Pancreatic adenomas developed in 27 treated and 1 untreated mastomys, and a metastasizing adenocarcinoma developed in 1 treated animal. All treated females, 3 treated males, and 1 untreated female developed multiple villous adenomas in the small intestine. One untreated female and 8 treated females developed mammary cancers, 4 of which metastasized. Primary tumors of other sites occurred infrequently.

This report covered the pathologic features, behavior, metastases, and results of transplantation of pure yolk sac carcinomas that were primary in the uterine horn of 8 mice; 6 mice were strain C3H and 2 were strain HR, and they varied from 10 to 23 months of age. Three of the mice had never been treated. Of the 5 that had, the treatment was different for each mouse. Therefore, treatment could not be correlated with tumor development. At least 5 mice were nulliparous; in fact they had never been mated, so in these some mechanism involving parthenogenesis must have been operative to account for the tumor. The tumors were identified as being primary in the uterus and occupied and distended the cavity of one uterine horn where they were polypoid or plaquelike. The neoplastic yolk cells replaced the endometrial stroma forming a support for the original endometrial glands. In time the tumor cells destroyed many of the endometrial glands. That the glands present in the primary uterine horn tumors were the original glands of the endometrium and not neoplastic glands was attested by their absence from the secondary neoplastic deposits in 4 mice in which the tumor had spread to areas outside the cavity of the uterus and from the neoplastic tissue of the tumor transplants in the recipient mice.

Adenocarcinoma of the gallbladder developed in 17 of 68 untreated and in 26 of 83 irradiated guinea pigs of inbred strains 2 and 13. The carcinomas spread widely by direct extension and through lymphatic and blood vessels to lymph nodes, mesenteries, omenta, abdominal wall, liver, lungs, bones, and spleen. Whole-body exposure to gamma or X-radiation increased both the number of tumors and metastases in male inbred guinea pigs but not in females. Significantly fewer (9 of 98) noninbred than inbred guinea pigs developed gallbladder carcinomas after irradiation. In 9 untreated noninbred guinea pigs gallbladder carcinomas were not found. Inasmuch as the effect of irradiation was not dose-dependent, an indirect systemic effect of irradiation was postulated. This is the first report on the occurrence of spontaneous gallbladder adenocarcinomas in guinea pigs.

This report describes the organization and functions of the Registry of Experimental Cancers and gives the chronology of events that led to its establishment. Currently 21,500 accessions have been coded; the vast majority are spontaneous and induced cancers, chiefly of rodents, and also a wide variety of nonneoplastic diseases. Accessions are accepted from contributors working in laboratories in this country and abroad. The material is available for study by responsible scientists, and a limited number of study sets is available for loan on request.