Possible retention of the estrogen-binding capacity after endocrine ablation therapy in the rat and human breast cancer
Nomura, Y.; Abe, Y.; Yamagata, J.; Takenaka, K.
Gan 67(1): 101-104
1976
ISSN/ISBN: 0016-450X PMID: 178562 Document Number: 109098
Retention of estrogen receptor in regrowing tumors long after endocrine ablation in rat and human breast cancer is reported. Mammary cancer was induced in Sprague-Dawley rats by 7,12-dimethylbenz(a)anthracene (DMBA). More than 10 weeks after oophorectomy, tumors that were continuously growing or recurrent after regression were again submitted to estrogen receptor assay. 4 of the 8 tumors did not contain estrogen receptor before oophorectomy; 2 of these responded temporarily and the other 2 did not respond. The estrogen receptor was not found after oophorectomy in any of these 4. In the other 4 with presence of estrogen receptor all showed some response to oophorectomy. All the recurrent tumors in these 4 rats maintained their ability to bind titrated estradiol specifically. There were no definite change of Ks or (Ns) values. In the 4 patients with breast cancer, the metastatic or recurrent tumors disappeared once or regressed after a major endocrine ablation operation. After a relatively long period of regression, the malignancy had recurred. Assay of estrogen receptor and estimation of associated constant (Ks) and concentration of binding sites ((Ns)) continued the same as determined before the ablative therapy. It is assumed that these tumors initially contained cells of 2 types: sensitive and autonomous. The recurrent tumor is thought to be composed of autonomous cells while the sensitive cells have been eliminated by withdrawal of their supporting hormone. Results seem to be contradictory to the concept of autonomy in recurrent breast cancer after hormonal manipulation. The secondary recurrent cancer may sometim es be successfully checked by another hormonal manipulation or by some blocking agents that compete with the estrogen-receptor complex formation.