Predicting the Incidence and Prognosis of Bone Metastatic Breast Cancer: A SEER-Based Observational Study

Background. To determinate the association relationship of breast cancer bone metastasis and cancer characteristics and molecular subtype. Furthermore, to evaluate the impact of molecular subtype on prevalence and prognosis of bone metastasis from the breast cancer base on a large population real-word program, the Surveillance, Epidemiology, and End Results (SEER) database. Methods. We collected and analyzed the data obtained from SEER, which showed molecular subtype information for each patient. The prevalence and outcome of bone metastasis in breast cancer were estimated as per the different molecular subtypes. Results. Occurrence of bone metastasis in conformity with four different molecular subtypes in all 42684 breast cancer patients was 6.2, 9.4, 7.9, and 6.4%, respectively. The most unfavorable subtype was the triple-negative breast cancer (TNBC), followed by the luminal A, luminal B, and HER2 subtypes (hazard ratio [HR] of luminal A compared with TNBC, 0.533, 95% confidence interval, 0.444-0.641; HR of luminal B, 0.482, 95% CI 0.419-0.555; HR of HER2 subtype, 0.542, 95% CI 0.484-0.608). Brain metastasis impacts overall survival (OS) (p<0.001) fundamentally, and visceral metastases also significantly decreased OS (p<0.001). Conclusion. Bone metastasis patients present a more favorable oncological survival consequence than other metastases, and the TNBC subtype with bone metastasis showed the poorest tumor outcome compared with the other three molecular subtypes.