Possible retention of the estrogen-binding capacity after endocrine ablation therapy in the rat and human breast cancer.

The estrogen-binding capacity of the regrowing tumors after endocrine ablation surgery was estimated in the rat and human breast cancer. All of 4 tumors that had not had the estrogen receptor before oophorectomy did not show the estrogen-binding capacity after the procedure, in the mammary cancer in the Sprague-Dawley rat induced by 7,12-dimethylbenz[a]anthracene, whereas all the 4 tumors that had the receptor before the procedure showed the binding capacity after oophorectomy. In 4 patients who had been subjected to the major endocrine ablation therapy because of metastatic breast cancer with effective response, the secondary metastatic deposits of cancer showed the estrogen-binding capacity long after the endocrine ablation. The fact that regrowing tumors after complete or partial regression of initial tumors by endocrine ablation retain the estrogen receptor seems to be contradictory to the classical concept of autonomy in recurrence of the breast cancer after hormonal manipulation.