Avoiding Surgery in Estrogen Receptor Positive Atypical Ductal Hyperplasia and In-situ Carcinoma Treated With Endocrine Treatment Trial

1\. Inclusion criteria:

1. Female patients aged ≥35 years.
2. Diagnosed with atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS), or lobular carcinoma in situ (LCIS) on core-needle biopsy, vacuum-assisted biopsy, or excisional biopsy.
3. Immunohistochemistry (IHC) performed on biopsy specimens confirming estrogen receptor (ER), progesterone receptor (PR), and HER2 status; eligible only if the ER Allred total score is ≥7 and HER2 status is negative.
4. All low- and intermediate-grade nuclear grades included; for high-grade lesions, only patients with a Ki-67 index ≤20% are eligible.
5. Lesion not definitely palpable on physical examination at diagnosis.
6. No prior breast surgery for ipsilateral or contralateral breast cancer, and no synchronous contralateral breast cancer.
7. Not diagnosed with pregnancy-associated breast cancer or breast cancer detected during lactation.
8. Negative serum or urine β-hCG prior to enrollment.
9. Provided written informed consent to participate in the study.

2\. Exclusion criteria:

1. Pregnant patients.
2. Patients with clinically significant psychiatric disorders (e.g., major depressive disorder) or those currently receiving psychiatric or antipsychotic medications.
3. Concomitant diagnosis of invasive breast cancer.
4. Evidence of axillary lymph node metastasis.
5. Carriers of BRCA1/2 mutations.
6. Male patients.
7. History of diagnosis or treatment for breast cancer.
8. Presence or history of other malignancies besides breast cancer.
9. Concomitant diagnosis of pleomorphic LCIS.