The prediction of hormonal dependency of mammary cancer.

The estrogen receptor protein (estrophilin) was determined in specimens from 359 primary breast cancers and from metastatic tumors of 214 patients. Ninety-eight patients were eventually treated by some form of endocrine therapy: 82 patients were treated by ablative therapy, and 16 by hormonal additive treatment. The records of 81 of the 98 patients whose tumors were characterized for estrogen receptor content and who had received some type of endocrine therapy were reviewed by a peer review group that assessed the objective data for these patients regarding objective remission or failure to treatment. A positive estrophilin determination was defined as receptor content greater than 250 fmole per gram of tumor for premenopausal females and greater than 750 fmole per gram of tumor for postmenopausal and previously castrated patients. Estrogen receptor determinations may be made from tumor specimens as small as 200 mg. Sixty-nine patients underwent some form of ablative therapy. Twenty-seven of these patients were found to have significant receptor determinations. Of those patients in whom a definite determination was made of their post-treatment response, roughly two-thirds experienced objective remissions. None of the 42 patients with negative estrogen receptor determination experienced an objective remission to ablative endocrine therapy. Only one of 6 patients with negative determinations benefited from additive hormonal therapy; 4 of 6 patients with positive determinations benefited from additive therapy. Not all women with receptor containing mammary cancer will respond favorably to endocrine therapy, but those patients whose tumors lack a critical amount of estrophilin have little chance of benefit from either endocrine ablation or hormone administration. The estrogen receptor content of the primary tumor indicates the hormonal dependency of the tumor and may be used to predict the response to endocrine treatment when recurrent disease appears.