Estimating mortality in women with triple-negative breast cancer: The 'ESTIMATE triple-negative' tool.

PURPOSE: Triple-negative breast cancer (TNBC) is associated with a high risk of breast cancer-specific mortality (BCSM). Estimating the risk of BCSM and non-BCSM in TNBC would aid clinical decision-making. We developed the tool 'ESTIMATE-TN', to assess BCSM, non-BCSM, and all-cause mortality in non-metastatic TNBC. METHODS: Using Surveillance, Epidemiology, and End Results (SEER), we created an interactive tool that provides a nonparametric estimate of the cumulative risk of BCSM and non-BCSM between years 0 and 7 from diagnosis, accounting for baseline clinical and pathologic variables, using Gray's subdistribution method. RESULTS: We included 37,293 women with TNBC diagnosed during 2010-2017. Most patients were White (71.9%) and aged 50-69 years (51.3%). Most tumour characteristics were high-grade (78.6%), T2 (42.4%), and N0 (69.5%). ESTIMATE-TN allows to input patient and tumour characteristics, and the preferred timeframe. For example, patients aged 50-59 years with a new diagnosis of T2, N1, high-grade TNBC have a risk of BCSM at 7 years of 30.8% (95% confidence interval [CI]: 26.3-35.4%) and a risk of non-BCSM over the same period of 2.8% (95% CI: 1.3-4.3%). After 3 years from initial diagnosis, the residual cumulative risks of BCSM and non-BCSM at 7 years are 17.4% (95% CI: 12.6-22.2%) and 1.1% (95% CI: 0-2.5%), respectively. CONCLUSIONS: ESTIMATE-TN is an interactive tool for TNBC that can be used to integrate population-based risks of BCSM and non-BCSM based on patient and tumour characteristics, facilitating our understanding of competing risks of death, which can aid clinical decision-making.