Abstract P2-10-01: Estimating risk of breast cancer-specific mortality (BCSM) and non-BCSM in patients with triple-negative breast cancer
Authors: Leone Jose P , Graham Noah , Leone Julieta , Tolaney Sara M , Leone Bernardo A , Freedman Rachel A , Hassett Michael J , Vallejo Carlos T , Winer Eric P , Lin Nancy U , Tayob Nabihah 
Published: March 2022

Background: Triple-negative breast cancer (TNBC) is associated with high risk of distant recurrence and death. At present, our ability to estimate risk of death from causes other than breast cancer is limited. Particularly among elderly patients (pts), who have been historically underrepresented in clinical trials. In pts with TNBC, assessing both risks is important for our treatment recommendations. The aim of this study was to evaluate risk of BCSM and non-BCSM in TNBC by patient (pt) and tumor characteristics. Methods: Using data from the Surveillance, Epidemiology, and End Results (SEER) program, we identified women diagnosed with non-metastatic invasive TNBC between 2010-2016. Fine and Gray regression was used to evaluate the association of BCSM with pre-specified variables including pt age, tumor size (T), nodal status (N), and tumor grade, while considering deaths from other causes as competing events. We then estimated cumulative risk of BCSM, non-BCSM and all-cause mortality within subgroups defined by baseline clinical and pathologic variables. We conducted a subset analysis of N0 pts older than 50 years, given that we anticipated this subgroup would have the most clinically useful balance between BCSM and non-BCSM. Results: We included 37,293 pts. Age distribution was: 27.1% &lt;50 years, 51.3% 50-69 years, 15.0% 70-79 years, and 6.6% ≥80 years. Among all pts, 42.4% presented with T2 tumors and 69.5% had N0 disease. In adjusted Fine and Gray regression, risks of BCSM were higher for pts aged &gt;80 years vs 50-69 years (Hazard ratio [HR] 1.62; 95% CI, [1.45 - 1.80]), T4 vs T1a (HR 8.51; 95% CI, [6.20 - 11.68]), N3 vs N0 (HR 6.31; 95% CI, [5.70 - 7.00]) and grade III/IV vs grade I (HR 2.10; 95% CI, [1.44 - 3.07]). The cumulative risk of BCSM in year 0-7 was 10.7% for N0, 27.9% for N1, 46.4% for N2 and 64.0% for N3. In contrast, the cumulative risk of non-BCSM over the same period ranged from 7.5% in N1 to 8.7% in N2. The table shows risks of BCSM, non-BCSM and all-cause mortality among pts with N0 disease by age at diagnosis and tumor size. Pts 50-69 years had an increasing cumulative risk of BCSM by tumor size up to 13.0% in those with T2 tumors, while the risk of non-BCSM ranged from 4.8% to 5.9%. Pts aged 70-79 years with T1a/b, N0 tumors had risks of BCSM that were approximately 60% lower than the risks of non-BCSM. In pts aged ≥80 years, the risk of non-BCSM increased and is significantly higher than BCSM in patients with T1b-T2 disease. Conclusions: The risk of BCSM in TNBC depends on traditional clinicopathologic factors and is in general, much higher than the risk of non-BCSM. However, the high risk of non-BCSM among older pts is substantial which needs to be taken into consideration when making treatment recommendations. An interactive tool to estimate risks of BCSM, non-BCSM and all-cause mortality for TNBC will be presented at the meeting.

BCSMnon-BCSMAll-cause mortalityCumulative risk (%) and 95% CICumulative risk (%) and 95% CICumulative risk (%) and 95% CIyears 0-7years 0-7years 0-7Tumor size among age 50-69, N0 onlyT1a2.6 (1.0 - 4.3)5.9 (3.2 - 8.6)8.5 (5.3 - 11.6)T1b3.9 (2.8 - 5.0)4.8 (3.3 - 6.3)8.7 (6.9 - 10.5)T1c8.1 (6.9 - 9.4)4.8 (3.9 - 5.8)13.0 (11.4 - 14.5)T213.0 (11.6 - 14.4)5.5 (4.4 - 6.5)18.5 (16.8 - 20.2)Tumor size among age 70-79, N0 onlyT1a6.1 (0 - 12.7)13.9 (7.0 - 20.9)20.0 (10.2 - 28.7)T1b5.3 (3.0 - 7.7)13.3 (9.0 - 17.7)18.6 (13.7 - 23.3)T1c11.0 (8.7 - 13.4)14.3 (11.4 - 17.2)25.3 (21.7 - 28.8)T221.0 (17.4 - 24.6)17.4 (13.4 - 21.5)38.5 (33.3 - 43.2)Tumor size among age ≥80, N0 onlyT1a6.6 (0 - 19.7)27.0 (11.0 - 43.1)33.7 (11.8 - 50.1)T1b7.1 (2.1 - 12.2)33.2 (23.2 - 43.2)40.3 (28.9 - 49.9)T1c8.4 (5.2 - 11.6)32.7 (26.4 - 39.0)41.1 (34.1 - 47.3)T222.7 (18.1 - 27.3)41.6 (34.2 - 49.1)64.3 (56.0 - 71.1)

Citation Format: Jose P Leone, Noah Graham, Julieta Leone, Sara M Tolaney, Bernardo A Leone, Rachel A Freedman, Michael J Hassett, Carlos T Vallejo, Eric P Winer, Nancy U Lin, Nabihah Tayob. Estimating risk of breast cancer-specific mortality (BCSM) and non-BCSM in patients with triple-negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-10-01.