Co-expression of steroid and HER2 receptors in breast carcinomas in a large (4,493 cases) population-based Polish study

Abstract

797 Background: In addition to well-established clinical prognostic and predictive factors (i.e. nodal status), the assessment of parameters such as oestrogen (ER), progesterone (PgR) and HER2 receptor status are needed to make an adequate diagnosis of breast cancer. The study reported here is part of a national HER2 screening project in Poland, which started in 2002 and is still ongoing. By April 2004, 11,557 cases of invasive breast carcinoma had been included. The aim of the study was to investigate the relationship between HER2 and ER/PgR status. Methods: The study was performed in 4,493 non-selected cases of breast cancer. The data originated from 14 oncology centres in Poland and were collected between April 2003 and March 2004. ER, PgR and HER2 receptor status were evaluated by immunohistochemistry (IHC). HER2 IHC results were classed by the DAKO criteria system as: 0, 1+, 2+ or 3+. The cases classed as 0, 1+ and 2+ were considered to have a negative HER2 status. The remaining cases (IHC 3+) were considered HER2 positive. Steroid receptor-positive cases were grouped by the presence of 10% or more positively stained cancer nuclei, regardless of the strength of the stain. A positive ER/PgR status was recorded when ER/PgR receptors were detected. A mixed group consisted of cases in which one steroid hormone was present. Results: The group described by IHC as 0, 1+ and 2+ showed the presence of at least one steroid receptor in more than two-thirds of all cases (71%, 80% and 79%, respectively). Among the tumours exhibiting HER2-receptor overexpression (IHC 3+), 52% were steroid-receptor positive. Conclusion: The results of this large population-based study indicate that there is a relationship between the expression of ER and PgR receptors and HER2 status. The probability of the existence of positive steroid receptor status in the clinically HER2-positive group (3+) was lower than in the clinically HER2-negative group (0, 1+, 2+). However, even so, more than half of the HER2-overexpressing patients were also steroid receptor positive. Taken together, these results emphasise the necessity of independent evaluation of both steroid receptors and HER2 status. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Roche Polska Roche Polska Roche Polska