Studies of the effect of perthane on spontaneous and transplanted mammary carcinoma in the C3H mouse.

DDD—2,2-bis-(para-chlorophenyl)-l,l-dichloroethane—a derivative of DDT—2,2-bis-(parachlorophenyl)-l,l,l-trichloroethane—causes se vere adrenal cortical atrophy in the dog (9, 15-17, 25). Larson et al. (9) found that the two chlorines in the 1-position of the ethane group were critical, with adrenal cortical atrophy failing to develop with the chlorine at the 3 or 1 position, or absent (Chart 1). These workers also demonstrated that, while the chlorines in the para-phenyl position are not essential, the phenyl rings must be present. Substitution of ethyl radicals for the chlorines in the para-phenyl position of DDD results in the formation of 2,2-bis-(para-ethylphenyl)-l,l-dichloroethane (Perthane)1 (Chart 1). Perthane has the same adreno-corticolytic effect in the dog as DDD (9). Shimkin and Wyman (19) have demonstrated that adrenalectomy in unbred C3H female mice of the Andervont strain, at the age of 4 weeks, de creases the incidence of spontaneous mammary carcinoma from 84.5 to 40 per cent. Martinez and Bittner (13) reported a 3.3 per cent incidence of complete regression and a 10 per cent incidence of partial regression of mammary tumors in mice after total bilateral adrenalectomy when the spon taneous tumors were 5-14 mm. in diameter. Al though histologie evidence of adrenocortical atro phy has not been reported in Perthane-fed mice, the possibility that physiological depression might occur has not been excluded by previous work. This consideration suggested to us that greater adrenal hypofunction might result from prolonged