Abstract PD1-07: Racial disparities in neoadjuvant chemosensitivity and survival in early breast cancer: A national database study
Authors: Roy Arya Mariam , Catalfamo Kayla , Attwood Kristopher , Gandhi Shipra 
Published: March 2023

Background: Neoadjuvant chemotherapy (NAC) is the standard of care for locally advanced breast cancer (BC). Patients (pts) who attained pathological complete response (pCR) with NAC have a better prognosis when compared to those who have residual disease (RD). We analyzed the association of race with neoadjuvant chemosensitivity in early BC and the overall survival (OS) based on the chemosensitivity.

Methods: We queried the National Cancer Database for early BC pts who received NAC from 2010-2016. Preoperative chemosensitivity was defined as very sensitive (VS) (ypT0/TisN0), sensitive (S) (pathological TNM stage less than clinical, excluding ypT0N0), and refractory (R) (pathological greater than or equal to clinical). Demographic, clinical, treatment, and survival rates were summarized by race focusing on neoadjuvant chemosensitivity. All associations were compared using Kruskal-Wallis, Pearson’s Chi-Squared, and Fisher’s Exact Tests. Multivariate cox models were generated for the OS. All analyses were conducted in RStudio v4.0.2 at a significance level of 0.05.

Results: A total of 103,605 pts who received NAC were analyzed. 43.2% (n= 44,796) were R, 34.4% (n= 35,638) were S and 22.4% (n= 23,171) pts were VS. The 3-year (yr) OS rates for R, S, VS groups were 81%, 88%, 95% respectively (rsp) (p&lt; 0.001). The 5-yr OS rates were 73%, 82%, 92% rsp (p &lt; 0.001). In the hormone-receptor positive HER2 negative (HR+) subtype, only 8.9% (n= 3,837) were VS, while among triple negative breast cancer (TNBC) subtype, 28.4% (n= 9,224) pts were VS, among HER2 positive (HER2+) subtype, 36.7% (n=9,665) pts were VS and in both subtypes around 28-36% were R as opposed to 58.4% with R disease among HR+ subtype. Among HR+ group, pts had more R disease regardless of race (all races R: 54-57%, p &lt; 0.001). Among HER2+ disease, Blacks had lower percentage of VS disease compared to other races (32% vs 37-40%, p&lt; 0.001). Among TNBC, more R disease was seen among Blacks compared to other races (38% vs 30-35%, p&lt; 0.001). In whole cohort, as expected, compared to pts with R disease, pts with S and VS disease had lower overall mortality risk (HR= 0.45, 95% CI= 0.43 – 0.46, P&lt; 0.001, HR= 0.20, 95% CI = 0.19- 0.21, p &lt; 0.001 rsp). In TNBC subgroup among pts with R disease, the median OS of Blacks was significantly lower compared to whites (71.9 vs 101.8 months, p &lt; 0.001). Among BC subtypes, the 3-yr and 5-yr OS for R (65%, 56%) and S groups (83%, 76%) were significantly lower in TNBC when compared to other subtypes (HR+ R: 3-yr- 88%, 5-yr- 79% and S: 3-yr- 90%, 5-yr- 83%; HER2+ R: 3-yr- 85%, 5-yr- 77% and S: 3-yr- 92%, 5-yr- 86%, p&lt; 0.001). In the whole cohort, Blacks with R, S, VS disease had significantly lower 3yr (73%, 85%, 94% rsp) and 5yr OS (63%, 78%, 91% rsp) compared to all other races and this was more prominent in the R and S groups (Table 1).

Conclusion: Blacks diagnosed with TNBC were more resistant while other races were more sensitive to NAC. In all BC subtypes, Blacks had lower 3-yr and 5-yr OS regardless of chemosensitivity (including those who attained pCR), though this disparity was more predominant among those with residual disease after NAC (resistant and sensitive group). Since Blacks who do not attain pCR have worse survival compared to other races, it highlights the need to design more effective and personalized treatment strategies for Blacks to help them attain pCR, especially in the TNBC subtype.

Table 1: Racial Disparities in Survival in Different Chemosensitivity Groups

Citation Format: Arya Mariam Roy, Kayla Catalfamo, Kristopher Attwood, Shipra Gandhi. Racial disparities in neoadjuvant chemosensitivity and survival in early breast cancer: A national database study. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD1-07.