Enhancer of zeste homolog 2 expression in invasive lobular carcinoma of the breast

Abstract

Objective Invasive lobular carcinoma (ILC) is the second biggest part of of breast cancer, but the prognosis of ILC is still indeterminate. Enhancer of Zeste homolog 2 (EZH2), the catalytic subunit of the polycomb repressive complex 2 (PRC2), is frequently overexpressed in various cancers types. This study explored the association between clinicopathologic characteristics and EZH2 expression. Methods We retrospectively reviewed the medical records of 54 patients with ILC, and 49 of them have been chosen for our study according to our criterion. Immunohistochemistry for EZH2 was undertaken. Results We defined ILC as discursive cells with a linear or nonlinear growth pattern. No statistically significant difference was found in most variables, such as multifocality, menstrual status, body mass index, tumor stage, lymph node stage, estrogen receptor, and progesterone receptor. However, nuclear grade had statistically significant difference and EZH2 expression was associated with high nuclear grade. In total, 80% of patients with nuclear grade 3 had an EZH2 score of 4, and 86% of patients with nuclear grade 1 had EZH2 scores of 1 and 2. Our cases had a score of 3 for tubule formation and a score of 1 for mitosis, and so the histologic grading consisted of grades 1 (7 cases) and 2 (42 cases) depending on the nuclear grade. Conclusion Although EZH2 could not be used for prognosis completely, EZH2 expression was associated with a high nuclear grade. Most ILCs have histologic grade 2 with nuclear grade 2 or 3. It is suggested that if ILC is diagnosed by separating the classic type and variants and considering both EZH2 expression and nuclear grade, EZH2 overexpression could help and the Nottingham grading system would be more accurate prognostic factor. Key words: Breast; Enhancer of Zeste homolog 2; Breast carcinoma