This is a non-interventional, prospective, single-arm, observational study describing the real-world effectiveness, safety, and PRO and HCRU data of ribociclib combined with adjuvant ET under conditions of routine clinical practice in HR+/HER2- EBC in premenopausal, perimenopausal and postmenopausal women, or men in Saudi Arabia.

This is a non-interventional, prospective, single-arm, observational study describing the real-world effectiveness, safety, and PRO and HCRU data of ribociclib combined with adjuvant ET under conditions of routine clinical practice in HR+/HER2- EBC in premenopausal, perimenopausal, and postmenopausal women or men in Saudi Arabia.

The study aims to recruit 177 patients who have been newly receiving ribociclib for up to 6 months prior to enrollment date, as per the locally approved label to which the physician has made an independent decision to prescribe ribociclib. Patients will be enrolled over a recruitment window of 9 months and will be followed up for 36 months to assess the study outcomes. It is planned to capture data at the following timepoints (+/- 1 month): Baseline, 3, 6, 12, 24, and 36 months. This is in line with the frequency of routine follow-up visits, per standard of care.

Data will be collected from patients' electronic medical records in the selected sites. The planned number of sites is 6, to be selected based on feasibility reports, considering the patient pool and research capabilities.

Participating sites' investigators will review all the available clinical files of patients whose ribociclib treatment decision has been made by their treating physician and will invite those who fulfill the eligibility criteria to participate in the study. Data will be entered into an electronic case report form (eCRF). All patients' data will remain anonymized, fulfilling the requirements of data protection. Data collected will include information on previous treatments received, disease history, and current treatment patterns and outcomes.

Participation in the study is not intended to change the routine treatment patients receive as determined by their treating physicians; all therapeutic decisions, as well as the type and timing of disease monitoring, will be at the discretion of the treating physician.

Inclusion Criteria:

1. Signed and dated Patient Informed Consent Form (PICF) obtained.
2. The patient is ≥ 18 years-old at the time of PICF signature.
3. Male or female patients with estrogen-receptor-positive and/or progesterone-receptor-positive BC.
4. Male or female patients with HER2- BC.
5. Patients who are currently receiving ribociclib in combination with adjuvant ET as per approved local label for up to 6 months prior the enrollment date.
6. Male or female patients with American Joint Committee on Cancer (AJCC) Anatomic Stage Group IIA(subset) /IIB or Anatomic Stage Group III EBC.
7. Female patients with known menopausal status (at the time of PICF signature or initiation of adjuvant ET, whichever occurs earlier), or male.

Exclusion Criteria:

1. Ribociclib-based treatment regimen beyond adjuvant therapy for EBC.
2. Patients are currently participating in any other clinical trials.
3. Patients who previously received any other CDK4/6 inhibitor.
4. Patients who refused to sign informed consent.
5. According to the investigator's opinion, the patient is an unlikely candidate to provide an accurate medical history and/or to obtain long-term follow-up information for any reason.

HR+/HER2- early breast cancer in premenopausal, perimenopausal, and postmenopausal women or men in Saudi Arabia.