Patterns of Distant Metastases in Patients With Triple-Negative Breast Cancer –– A Population-Based Study

Background Currently, the prognosis of triple-negative breast cancer (TNBC) patients remained poor mainly due to resistance, recurrence, metastasis and severe side effects. The study provided systematic insights into the patterns of TNBC distant metastases (DM), as well as investigating the related elements for the prognosis prediction of TNBC patients on the basis of on large sample. Methods We screened eligible patients with triple-negative breast cancer from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015. Besides, we analyzed differences in baseline characteristics among patients with diverse modes of metastasis. Meanwhile, we calculated proportional mortality ratio (PMR) and the expression of proportional trends in different patients. Subsequently, Kaplan-Meier (KM) analysis was employed to investigate the survival outcomes. Finally, the predictive and prognostic factors of DM were identified. Results In this study, we included 24,822 TNBC patients, including 1,026 DM patients and 23,796 non-DM patients. At the time of initial diagnosis, 4.1% of patients had DM, and 36.9% had multiple metastases. According to the study, the most common sites of metastasis in DM patients were bone (251 cases) and lung (244 cases), while the least common organ of metastasis was brain (37 cases). Age, tumor grade, T, N and marital status were deemed as risk elements of DM. T stage, insurance status, marital status, surgery treatment, chemotherapy, number of metastatic sites and metastatic sites also effect the diagnosis of DM significantly. Conclusion Our study showed that the most common site of metastasis in TNBC patients with DM was bone and the least common site was brain. Different modes of metastasis have different survival and prognostic characteristics. Thus, our research may have important implications for the clinical practice of TNBC patients in the future.