Postmenopausal women with hormone receptor-positive breast cancer are now prescribed aromatase inhibitors with 5 years or longer durations of therapy as recommended by clinical guidelines, which contributes to reducing breast cancer recurrence. However, aromatase inhibitors treatment is associated with a high incidence of musculoskeletal symptoms (MSS), often described as symmetrical pain, soreness in the joints, musculoskeletal pain, and joint stiffness, which even leads to bone loss, osteoporosis, and fractures. MSS reduces patients' quality of life and compliance with aromatase inhibitors therapy in up to one-half of women undergoing adjuvant aromatase inhibitors therapy, potentially compromising breast cancer outcomes. Therefore, this study aimed to monitor the musculoskeletal health of breast cancer patients during endocrine therapy to provide references for clinical practice.

Inclusion Criteria:

1. Postoperative early breast cancer；
2. Hormone receptor-positive breast cancer diagnosed by pathology；
3. Aromatase inhibitor therapy (e.g., anastrozole, letrozole, exemestane) was initiated within 3 months;
4. Postmenopausal women, or premenopausal or perimenopausal women taking ovarian function inhibitors;
5. Informed consent and voluntary participation in the study.

Exclusion Criteria:

1. Breast cancer recurrence or distant metastasis;
2. With other malignant tumors;
3. With cognitive or psychiatric disorders.

Participant eligibility is based on self-representation of gender identity.

Postoperative patients with hormone receptor-positive breast cancer and treated with aromatase inhibitors in Shanghai Cancer Center, Fudan University, Shanghai, China.

There is no plan to make individual participant data available to other researchers.