Pregnancy and Tumor Growth

The relationship between pregnancy and tumor development hae been investigated by a number of observers, whose multe have been, however, in many instances contradictory. For example, Moreau (1) and Herzog (2) found that transplanted tumors grow with unusual rapidity in pregnant animale. Haaland (3), on the other hand, maintained that pregnsncy exerts a markedly restraining influence on the growth of transplanted tumors, which oontinue to develop in their umial faahion after parturition. Bmhford and Murray (4) hold that “pregnancy” in the female “and full sexual activity in the male constitute no bar to successful traxisplantation.” Uhlenhuth and Weidane (5) observed retardation in the growth of tumors during pregnancy and also more frequent spontaneous retrogression. Bridl.6 (6) noticed a low percentage of positive inoculations in pregnant animals, and Ehrlich (7) observed that inoculations into animals bearing young wm frequently followed by negative results and that in those successfully inoculated the growth of the tumor was greatly retarded. Then, again, Albrecht and Hecht (8) maintained that pregnancy affects the growth of tumors just aa little as the presence of a tumor influences conception or gravidity. Cuenot and Mercier (9) reported a moat interesting observation. They noticed that Borrel’s tumor “B,” which rarely underwent spontaneous absorption, if inoculated before fecundation developed during gestation and receded during lactation. The tumor, however, did not regreee if one mouse only waa born, thua leaving the activity of the mammary gland at a minimum. Neither did absorption occur even in the presence of several young, if the tumor was so situated that its vasculari-