Changes of steroid hormone receptor content by chemotherapy and/or endocrine therapy in advanced breast cancer

In several sequences during the progression of cancer, the authors assayed estrogen receptors(ER) in 940 breast cancers and progesterone receptors(PgR) in 773 cancers. The percentages of ER+ and PgR+ cancers diminished according to the progression of malignancy. Sequential assays of ER and PgR were carried out in primary tumors and in the metastatic tumors at the first recurrence in 42 patients. During the disease-free interval, 10 (37%) of 27 ER+ tumors changed to ER- and all 15 ER- tumors remained negative. The hormone receptors were assayed before the treatments and after the tumor relapsed following regression or after the progression of cancer. The change of ER and PgR in 99 patients with advanced breast cancer were studied according to the type of systemic treatments. Through endocrine therapy, marked changes from ER+ to ER-, were noted (by antiestrogens, 47% [7/15]; by adreno-oophorectomy, 61% [11/18]). Almost no breast cancers changed from ER- to Er+ during the endocrine therapy (by antiestrogen, 1/6; by adreno-oophorectomy, 0/10). All of six PgR+ tumors changed to PgR- after therapy. By chemotherapy treatment, 44% (4/9) ER+ cancers became ER-, while 19% (3/16) ER- tumors changed to ER+. After the simultaneous combination of chemotherapy and endocrine therapy, 67% (10/15) of ER+ cancers changed to ER-, and 20% (2/10) of ER- tumors changed to ER+. Through the intervention of more than two kinds of chemotherapy and/or endocrine therapy between the first treatment and the last therapy, 79% (19/24) ER+ breast cancers changed to ER-. Thus, ER and PgR contents of breast cancer gradually became negative as the malignancy progressed, and with some kinds of treatments particularly including endocrine therapy. The significance of changes in hormone receptors after therapy was discussed.