Abstract PS6-13: Population-based tool to estimate residual risks of breast cancer specific mortality (BCSM) and non-BCSM
Authors: Leone Jose P , Tolaney Sara M , Leone Bernardo A , Freedman Rachel A , Hassett Michael J , Leone Julieta , Vallejo Carlos T , Winer Eric P , Lin Nancy U , Tayob Nabihah 
Published: February 2021

Abstract
Background: The risk of breast cancer death persists for at least 20 years from diagnosis. Most reports describing this risk have been based on selected patients (pts) enrolled into clinical trials. These studies report absolute risks at fixed timepoints (i.e. 10 or 20 years) and do not consider the dynamic changes in risks over time. The aim of this study was to develop a tool to calculate residual risks of BCSM and non-BCSM based on individual pt and tumor characteristics, at any given time after breast cancer diagnosis. Methods: Using data from the Surveillance, Epidemiology, and End Results (SEER) program, we identified women diagnosed with non-metastatic invasive breast cancer between 1990-2005, with one primary cancer in their lifetime, and known hormone receptor (HR) status. We estimated the effect of baseline clinical and pathologic variables known to be prognostic, including pt age, HR status, tumor size (T), nodal status (N), and tumor grade, on residual cumulative risks of BCSM and non-BCSM over time. The tool generates the residual death risk (RDR), which is a nonparametric estimate of the cumulative risk of BCSM and non-BCSM by year 20 after any given time from initial diagnosis, among patients defined by baseline clinical and pathologic variables using the method of Gray (1988) implemented in the cmprsk package in R. Results: We included 235,015 pts (median follow-up = 14 years). Among all breast cancer deaths, the proportion occurring after 5 years was 60% for HR+ vs 24% for HR- (p&lt;0.001). The table shows risks of BCSM and non-BCSM by HR and N status. The cumulative risk of BCSM in year 5-20 ranged from 4.2% in HR+ T1a N0 to 50.1% in HR+ N3. Using the RDR tool, a 54 year-old pt, diagnosed 7 years prior with a HR+, T1c, N1, grade 2 breast cancer, has a 16.6% residual cumulative risk of BCSM over the following 13 years, and a residual cumulative risk of non-BCSM over the same period of 4.0%. For a 66 year-old pt, diagnosed 10 years prior with a HR+, T1c, N0, grade 1 breast cancer, her residual cumulative risk of BCSM over the following 10 years is 2.9%, and her residual cumulative risk of non-BCSM over the same period is 10.0%. For a 45 year-old pt, diagnosed 8 years prior with a HR-, T2, N1, grade 3 breast cancer, her residual cumulative risks of BCSM and non-BCSM over the following 12 years are 4.4% and 4.9%, respectively. Conclusions: For HR+ breast cancer, risks of BCSM remain high beyond 5 years from diagnosis. For HR- breast cancer, the risk of BCSM is highest within 5 years from diagnosis; however, risks beyond 5 years are still considerable. The RDR tool provides population-based long-term estimates of cumulative risk of BCSM and non-BCSM over time, based on individual pt and tumor characteristics.
BCSMnon-BCSMAll-cause mortality% Event-FreeCumulative risk (%)Cumulative risk (%)Cumulative risk (%)at 5 yat 10 yy 5-20y 0-20y 0-20y 0-20Nodal status by HR status (any T)HR+N097.293.98.610.633.243.8N192.183.920.025.225.550.8N281.566.236.145.621.266.8N367.749.150.163.116.179.2HR-N089.285.47.317.022.739.7N174.268.312.234.317.051.3N257.049.320.053.514.568.0N340.733.526.268.79.378.0Tumor size among N0 onlyHR+T1a99.097.64.25.030.435.4T1b98.997.25.15.934.440.2T1c97.694.38.710.532.943.3HR-T1a97.394.74.97.323.030.3T1b95.191.96.210.527.137.7T1c91.787.97.514.823.037.8
Citation Format: Jose P Leone, Sara M Tolaney, Bernardo A Leone, Rachel A Freedman, Michael J Hassett, Julieta Leone, Carlos T Vallejo, Eric P Winer, Nancy U Lin, Nabihah Tayob. Population-based tool to estimate residual risks of breast cancer specific mortality (BCSM) and non-BCSM [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-13.