Clinical characteristics, prognosis, and prognostic factors of patients with second primary triple-negative breast cancer: a study based on Surveillance, Epidemiology, and End Results database

This study examined the characteristics of tumors, treatments, and survival outcomes, with a particular focus on the survival-related factors of second primary triple-negative breast cancer (TNBC) in comparison to first primary TNBC. The Surveillance, Epidemiology, and End Results database was utilized to identify and enroll patients diagnosed with TNBC between the years 2010 and 2015. The outcomes of this study were 3-year and 5-year breast cancer-specific survival (BCSS). The multivariate competing risk model was conducted to explore the association between the second primary cancer and BCSS and to estimate risk factors for BCSS of both first and second primary TNBC. The hazard ratio and 95% confidence interval (CI) were evaluation indices. Our study demonstrated that age, histological grade III/IV, high T stage, high N stage, and TNBC were associated with a decreased 3-year and 5-year BCSS in both first and second primary TNBC. Family income ≥$60 000 per year (hazard ratio: 0.68, 95% CI: 0.48-0.95, P = 0.026) correlated with better 3-year BCSS in patients with second primary TNBC. Breast-conserving surgery, mastectomy, and the interval between two cancer diagnoses >3 years were associated with increased 3-year and 5-year BCSS in patients with second primary TNBC (all P < 0.05). This paper reveals a worse survival of second primary TNBC. Great attention should be paid to the prognosis of patients with second primary TNBC.