Therefore, this study aims to systematically clarify the clinicopathological features of mucinous carcinomas in older women by comparing the classical factors, such as type A/B, estrogen receptor (ER), progesterone receptor (PgR), HER2, nuclear grade, and Ki-67 score, as well as the expression of neuroendocrine and apocrine markers, with those from young to middle-aged women. Here, ESR1 is linked to mucinous adenocarcinoma.