Sarcomatous lesions in CBA female mice treated with 1,2-dimethylhydrazine: independent primaries or metastases?

CBA female mice treated with 1,2-dimethylhydrazine (DMH) alone or in combination with oestradiol dipropionate (EP) or ascorbic acid (AA) developed, as expected, a high incidence of uterine sarcomas. In addition, sarcomatous lesions at unusual sites (mainly in the forestomach) were evident. The incidence of sarcomatous lesions at other sites was 53/220 in mice having uterine sarcomas and 0/186 in mice treated with DMH but without uterine sarcomas. The difference between the two groups was highly statistically significant (P < 0.001) and demonstrates non-coincidental association of the above sarcomatous lesions with uterine sarcomas. Uterine sarcomas which presented in association with lesions at other sites were of a larger size than those found in isolation, and the difference in weights in three out of four groups was statistically significant (P = 0.008, 0.035 and 0.011). Histologically, sarcomatous lesions were similar in structure to those of uterine sarcomas, i.e. were of a fibroblastic-histiocytic nature with admixture of giant cells. On the basis of the above data the sarcomatous lesions described appear to represent uterine sarcoma metastases rather than independent primary tumours. AA did not have any influence on carcinogenesis induced by DMH alone but inhibited the growth of uterine sarcomas (whether or not they were associated with other sarcomatous lesions) induced by DMH combined with oestradiol dipropionate.