Overview

The goal of this observational study is to learn about the effects of using ribociclib in combination with physician-selected endocrine therapy as adjuvant therapy for patients with early high-risk HR+HER2- breast cancer. The main question it aims to answer is:

Whether it is effective and safe to use ribociclib in combination with physician-selected endocrine therapy as adjuvant therapy for patients with early high-risk HR+HER2- breast cancer? Participants will receive ribociclib (at a dose of 400mg per day for 3 weeks, followed by 1 week off, 4 weeks for 1 cycle) plus physician-selected endocrine therapy for three years. During the follow-up, their relevant clinical data will be recorded.

Eligibility

Inclusion Criteria:

1. Before any trial-related procedures, sign a written informed consent, and be willing and able to follow the planned visits, research treatment, laboratory examination and other test procedures;
2. Age 18-80 years old, female (both pre/post menopausal);
3. The patient's initial diagnostic tissue specimens were confirmed to be HR+, HER2- early high-risk invasive breast cancer without evidence of disease recurrence or distant metastasis.
4. The patient must have undergone radical surgery for the primary breast tumor. The cut edge of the removed specimen must be free from histological tumor residue (including invasive breast cancer or ductal carcinoma in situ [DCIS]). If supraclavicular or internal breast lymph nodes are considered for metastasis but cannot be surgically removed, radiotherapy should be carried out in the remaining lymph node drainage area in accordance with local guidelines.
5. After surgical resection, the tumor was completely removed, and there was no tumor at the end of the surgical specimen microscope, and it belonged to one of the following stages:
   • Pathological Stage IIB or III
   • Pathological Stage IIA as listed below:
   • N1 or N0, and: grade 3, or grade 2, meeting any of the following criteria:

     ( Ki67 ≥ 20%, or Oncotype DX breast recurrence score ≥ 26, or MammaPrint
     classification of high risk)
     Attention:
       -  For patients with tumor anatomical stage IIA N0: Patients are ineligible if
          Grade 1 or Unknown (Gx).
       -  Patients receiving neoadjuvant therapy must meet the above criteria in any
          preoperative staging/samples and/or surgical specimens (for staging, if Stage
          IIA, N0, also including grading and Ki67 or gene expression testing).
       -  AJCC 8th edition anatomic staging requirements determine T, N, and M
          categories. ALND is the preferred method for axillary lymph node staging;
          however, SLN dissection may be used to determine N classification in the
          following situations: No metastasis in the SLN (patients are considered as
          pN0); Slight metastasis in the SLN (patient considered as pN1mi); Patients with
          T1-2 and no clinically significant nodes before surgery, no neoadjuvant
          chemotherapy, at least 1 macrometastasis in 1 or 2 SLNs, no clustered swollen
          lymph nodes or severe extra-lymph node diseases during SLN clearance (patients
          are considered as pN1).

6. A maximum of 12 months from surgery to enrollment.

7. Patients with an ECOG score of ≤3, allowing the combination of other asymptomatic

underlying diseases.

8. The patient can swallow oral endocrine drugs, regardless of the type of endocrine

drugs.

9. The patient agrees to take paraffin samples from the primary lesions (including the

     primary lesions and lymph nodes), tumor tissue and blood samples from the recurrent
     lesions for future exploratory biomarker analyses

10. The patient has completed (neo)adjuvant chemotherapy and standard radiotherapy (when

indicated) in accordance with clinical practice guidelines.

Exclusion Criteria:

1. The patient has received any CDK4/6 inhibitors in the past.
2. Metastatic diseases (including contralateral axillary lymph nodes)
3. Patients have received ET (tamoxifen or aromatase inhibitors or raloxifene) for the prevention of breast cancer.
4. Unwilling to participate in the quality of life questionnaire score or provide tissue samples at the time of recurrence