Oestrogen and progesterone receptor estimation by enzyme-immunoassay on tissues removed before and after a modified radical mastectomy.

To investigate the possibility of receptor degradation due to devascularization of the tumour during mastectomy, oestrogen and progesterone receptors (ER and PgR) were measured by an enzyme-immunoassay (EIA) in 59 cases of primary breast cancer on samples taken before and after performing a modified radical mastectomy. Pre- and post-mastectomy samples from the same patient were analysed simultaneously in the same assay run. There was 86.4% and 93.2% agreement respectively in ER and PgR status between samples removed before and after surgery. When actual values were analysed, the post-mastectomy values were higher or lower than pre-mastectomy values with similar frequency. These random variations could be attributed to heterogeneous distribution of receptors within a tumour. The overall correlation between pre- and post-mastectomy values was excellent (ER: r = 0.810, P < 0.001; PgR: r = 0.706, P < 0.001). Devascularization of the tumour during surgery does not seem to affect the integrity of the epitopes recognized by monoclonal antibodies against ER and PgR to any significant extent.