Elastosis in Breast Cancer as a Surrogate Marker for Estrogen Receptor Positivity

OBJECTIVES: We sought to describe the occurrence of stromal elastosis in breast carcinoma among Omani female patients using semi-quantitative methods. We also sought to investigate the relationship between stromal elastosis and estrogen receptor (ER), progesterone receptor (PR), HER2/neu receptor tumor grade, and Ki-67 index. Furthermore, we evaluated the diagnostic accuracy of hematoxylin and eosin (H&E) stain method in quantifying elastosis compared to Elastin van Gieson (EVG) stain and if elastosis can be used as prognostic marker for overall survival. METHODS: The content of elastic tissue in primary infiltrating carcinomas of the breast was assessed using semi-quantitative methods (H&E and EVG stains) in 80 female Omani patients by two independent pathologists. Data of primary breast cancer patients who were not treated with neoadjuvant therapy from 2009 to 2019 at the Armed Forces Hospital of Oman were collected from medical records. Demographic and clinical data, including age, menstrual status, tumor type and grade, ER, PR, HER2/neu status, and Ki-67 index were obtained. Follow-up data, including clinical remission, evidence of metastasis, death, or lost follow-up were traced from medical records. RESULTS: Among the 80 cases studied, 80.0% were diagnosed with invasive ductal carcinoma, not otherwise specified, while 12.6% were diagnosed with infiltrating lobular carcinoma. Interobserver agreement of grading elastosis on H&E and EVG was strong (Kappa coefficient = 0.858). Using EVG, absent elastosis, grade 1, grade 2, and grade 3 were observed in 12.5%, 37.5%, 30.0%, and 20.0%, respectively. A statistically significant relationship between high elastosis and ER positivity (p = 0.015) and negative HER2/neu receptor (p = 0.045) was observed. No statistically significant relationship between elastosis and other entities, including menopausal status, tumor type and grade, PR, Ki-67, and prognosis. The sensitivity and specificity of quantifying elastosis on H&E stained sections compared to EVG stain (the gold standard) were 68.75% and 96.88%, respectively. CONCLUSIONS: Elastosis occurrence varies in different breast cancer populations. Elastosis can be considered a surrogate marker for estrogen positivity and HER2/neu negativity in breast cancer patients. In addition, H&E stain is considered an accurate method for quantifying elastosis compared to the EVG staining method.