Immunohistochemical assessment of oestrogen and progesterone receptors: correlations with the DCC method and clinical outcome in primary breast cancer patients

Two different methods to determine steroid receptors were analysed with res pect to their ability to estimate prognosis in primary breast cancer patien ts. The immunohistochemical assay (IHA) was compared with the dextran-coate d charcoal (DCC) method of receptor determination. A random sample of 281 p atients with invasive ductal carcinoma was drawn from 841 consecutive patie nts with primary breast carcinoma treated at Odense University Hospital bet ween l January 1980 and 31 December 1990. Receptor determination by the DCC method had been carried out previously in 164 patients for the oestrogen r eceptor and in 132 patients for the progesterone receptor. The former group war reassessed by IHA with the antibody ER1D5, and the latter with the ant ibody PgR-ICA. The median follow-up time was 8.3 years (range 2.9-12.9 year s). A cutoff of zero was used for the DCC: method. Immunohistochemical resu lts were quantified by counting in systematically random sampled fields of vision and values above zero were considered to be positive. Overall agreem ent of positive and negative cases was 86% for the oestrogen receptor and 8 3% for the progesterone receptor. Although the study included a limited num ber of patients, receptor positive cases fared better than negative cases i n all situations. Investigation of the prognostic power revealed that class ification based on IHA allowed better discrimination of patients than class ification based on the DCC method. The reason for this difference might be because distinction between benign and malignant tissue is possible using t he IHA method. Thus, MA results appear to be more clinically relevant. (C) 2000 Harcourt Publishers Ltd.