Simultaneous and sequential determinations of steroid hormone receptors in human breast cancer. Influence of intervening therapy.

Estrogen (ER), progesterone (PgR), and androgen (AR) receptors were measured in two simultaneous or subsequent specimens taken each from 259 patients with breast cancer. We studied in 182 patients results from receptor assays, either from one tumor or from the primary tumor, and a lymph node metastasis, and in 77 sequential biopsies with or without intervening therapy. All assays were performed in a single laboratory, considering 10 fmol/mg cytosol protein bound ligand as receptor positive. The concordance rate in simultaneous ER assays was 85%; however, we found a considerable high discordance rate for PgR in primary tumor and lymph node metastasis (25%). The overall discordance rate in sequential biopsies for ER was 38% and for PgR 25%. This discordance rate was primarily dependent on the receptor quality of the first assay (ER+: 50%, ER-: 24%, PgR+: 68%, PgR-: 9%). Considering only the ER+ and PgR+ cases, we found the greatest discordance rate in the patients having endocrine treatment following the first biopsy (55% and 84%, respectively). We conclude that the receptor status of one tumor biopsy is highly representative for other tumor or lymph node biopsies. Because of the high discordance rate of primarily receptor + cases in subsequent recurrences, the receptor quality of these lesions should be analyzed whenever possible.