Immunohistochemical evaluation for hormone receptors in breast cancer: a practically useful evaluation system and handling protocol.

This article reviews the current status of hormone receptor evaluation in and out of Japan, and introduces the proposed working protocol of the task force for Adequate immunohistochemical evaluation in routine practice for breast cancer by the Japanese Breast Cancer Society. Understanding the principles and the developmental process of immunohistochemistry helps us to utilize a scoring system adequately. Methodologies of hormone receptor examination and immunohistochemical procedures are briefly introduced. Each scoring system is based on different principles. The proposed working protocol takes into account the reproducibility of results among observers, institutions and staining procedures, which is justified based on the current situation in Japan. Future directions for the standardization of immunohistochemical hormone receptor evaluation are also described.