ESR1 and neoplasm: The ER-positive/PR-positive group included the highest proportion of patients with less aggressive tumor characteristics, including tumor size smaller than 2 cm, negative lymph node status, adjusted AJCC sixth edition stage I, and tumor grade I to II, and the proportions of these patients gradually decreased from ER-positive/PR-positive to ER-positive/PR-negative to ER-negative/PR-positive to ER-negative/PR-negative tumors (Table 1).