BACKGROUND: This retrospective study aimed to evaluate the prognostic roles of distant metastatic patterns in de novo metastatic triple-negative breast cancer to explore the roles of surgery on the primary tumor and to characterize the prognostic factors of organ-specific metastasis.

MATERIAL AND METHODS: Data were obtained from the Surveillance, Epidemiology, and End Results program. Kaplan-Meier analyses and log-rank tests were employed to compare survival outcomes among variables. The Cox proportional hazards model was used to assess risk factors for survival. The key endpoints were overall survival and breast cancer-specific survival.

RESULTS: A total of 1888 patients were eligible. Distant metastatic site displayed a significant prognostic impact on survival. Using liver metastasis as the reference, overall survival was higher for bone (hazard ratio [HR] 0.770, 95% confidence interval [CI] 0.634–0.935, P=0.008) and lung (HR 0.747, 95% CI 0.612–0.911, P=0.004) metastases. Using patients with brain metastasis as the reference, patients with bone (HR 0.516, 95% CI 0.392–0.680, P<0.001), lung (HR 0.500, 95% CI 0.379–0.661, P<0.001) or liver (HR 0.670, 95% CI 0.496–0.905, P=0.009) metastases exhibited better overall survival. Single-site metastatic patients who received surgery for the primary tumor had more favorable overall survival (P<0.001) and breast cancer-specific survival (P<0.001) than those who did not. Additionally, age, insurance status, chemotherapy, and surgery affected overall survival for patients with isolated bone metastasis; chemotherapy, and surgery affected overall survival for patients with isolated lung metastasis; and insurance status, chemotherapy, and surgery affected overall survival for patients with isolated liver metastasis.

CONCLUSIONS: Our study verified the specific prognostic significance of distant metastatic site for metastatic triple-negative breast cancer at diagnosis. Surgery on the primary tumor significantly improved survival for patients with single distant metastasis. The identified prognostic factors contributed to evaluating the prognoses for distant metastatic triple-negative breast cancer patients.

Keywords: SEER Program, Triple Negative Breast Neoplasms, Bone Neoplasms, Breast, Chemotherapy, Adjuvant, Liver Neoplasms, Mastectomy, Risk Assessment, Risk Factors