Further Studies on Active Milk Influence in Breast Cancer Production in Mice. ∗

Abstract

Conclusions

The “breast cancer producing influence” is an actual active “influence” present in the milk of high cancer stock females. It is probably present and active during the entire lactation period.

The active influence may be transferred by the inoculation of spleen, thymus, and lactating mammary gland tissue from cancerous stock animals. The active influence probably is not present (or has been destroyed) in the liver of high tumor stock mice. The active influence may be given to 4-week-old females by feeding-by-mouth milk obtained from lactating females of a cancerous stock. Fostered females of low breast tumor strains need not develop breast tumors to transfer the active milk influence by nursing. An active milk influence may be necessary for the development of induced estrogenic breast tumors.

(A future publication will show that a low breast tumor strain of mice may “acquire” an active milk influence at any time, resulting in a high breast tumor strain.)