Abstract Purpose Hormone receptor-positive type of breast cancer is typically treated with hormone therapy (HT), including tamoxifen and aromatase inhibitors (AI). However, long-term use of HT may increase the risks of endometrial cancer, vaginal dryness, and osteoporosis. To minimize the risks, breast surgeons should schedule regular follow-up with gynecologists and arrange bone mass density (BMD) examination. Using the Plan-Do-Study-Act (PDSA) methodology, we aimed to increase cross-team care with gynecology department and to promote BMD examination for breast cancer patients receiving HT. Methods We formed a multidisciplinary team including breast surgery department and gynecologic department in our hospital that care for female patients with breast cancer and related side effects. We arranged a lecture for all collaborative doctors, introducing our aims, interventions, and measurement strategies to test in multiple PDSA cycles. The interventions with standardized criteria include: (1) a gynecologic consultation, triggered if a patient initially receive tamoxifen and (2) a BMD examination, triggered if a patient initially receive AI. The triggering mechanism is embedded in the ambulatory alarming system. Both the intervention rates were tracked during PDSA cycle 1 in 2023 and compared with baseline rates in 2020-2022. Adherence to the plan was maintained and measured using data analytic reports and chart audits. Results The gynecologic consultation rate during PDSA cycle 1 is significantly higher than the baseline, which is 40.4% and 22.4% (p = 0.006), respectively. In patients who received tamoxifen, 6-month-consultation rate during PDSA cycle 1 is also significantly higher than the baseline group, which is 77.77% and 42.9% (p = 0.005), respectively. The median time from HT therapy to first gynecologic consultation decreased from 51 days to 28 days. Furthermore, the baseline BMD testing rate before our intervention was 30.6%. This increased to 48.3% during PDSA cycle 1. Conclusion Standardized gynecologic consultation criteria led to earlier gynecologic consultation in breast cancer patients receiving tamoxifen and higher BMD test rates in patients receiving AI. Future PDSA cycles will focus on assessing the frequency of subsequent gynecologic encounters in patients who received a triggered gynecologic consult. Citation Format: Chiu Ching-Wen, Tam Ka-Wai, Su Chih-Ming, Wu Hsueh-Chi. Building a standard methodology: Early Gynecologic Consultation and Bone Mass Density Examination in Breast Cancer Patients Receiving Endocrine Therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-10-08.