Importantly, our “click‐to‐sense” probe 1 labeled the breast cancer tissues with similar mean fluorescence intensity, regardless of IDC subtypes such as estrogen receptor (ER) or human epidermal growth factor receptor 2 (HER2) status, so as of DCIS subtypes for different ER status (Figure S4, Supporting Information). The gene discussed is ESR1; the disease is ductal breast carcinoma in situ.