Abstract: Objective: To explore the correlation between ultrasound imaging features of T1-stage breast cancer and the expression of
estrogen receptor （ER）, progesterone receptor （PR）, human epidermal growth factor receptor 2 （HER-2）, and Ki-67. Methods: A
retrospective collection of medical records of 493 patients confirmed with solitary malignant breast tumors from January 2012 to June
2021 was conducted. Ultrasound features and immunohistochemical results were recorded, and their correlation was analyzed. Results:
The positive rates of ER, PR, HER-2, and Ki-67 were 78.09%, 67.34%, 21.10%, and 71.60%, respectively. ER expression was
positively correlated with PR expression, while HER-2 expression was negatively correlated with ER and PR expression. Ki-67
expression was positively correlated with HER-2 expression and negatively correlated with ER and PR expression. ER-positive
expression was associated with irregular morphology, irregular margins, interstitial fat invasion, and high echo halos in ultrasound
features. PR-positive expression was associated with internal lesion components and axillary lymph node metastasis in ultrasound
features. Ki-67-positive expression was associated with unclear boundaries, interstitial fat invasion, and high echo halos in ultrasound
features, with statistical significance （P<0.05）. Conclusion: Ultrasound features of T1-stage breast cancer are correlated with the
expression of ER, PR, and Ki-67. Changes in ultrasound images can provide indications of tumor biological behavior, offering valuable
references for clinical decision-making.

Key words: T1-stage breast cancer, ultrasound features, estrogen receptor, progesterone receptor, human epidermal growth factor
receptor 2