CHANGE OF ESTROGEN-RECEPTORS LEVEL IN TRANSPLANTED MAMMARY-TUMORS OF C3H SN MICE DUE TO A MODIFIED HORMONAL ENVIRONMENT/

Studies were undertaken on the effect of various hormonal environment on the growth of transplanted mammary tumors in C3H/Sn mice, as well a s on the level of estrogen receptors in these tumors. The transplanted tumors have been found to respond to such a modification of the hormo nal environment by changing the quantity of estrogen receptors in them . The presence or absence of estrogen receptors in tumors depended on a hormonal background against which the tumors developed. Obviously, t he time period within which change has occurred in the receptor status of tumors must be taken into account by the clinicians who prescribe hormonal therapy to patients. This time period must be shorter than th e therapy course proper.