Abstract P6-01-03: Tumor-infiltrating lymphocytes (TILs) and 21-gene recurrence score in 1,883 patients with ER+/HER2- breast cancer

Abstract

Abstract Background: In ER+/HER2- breast cancer, several lines of evidence suggest that tumors with high level of tumor-infiltrating lymphocytes (TILs) have a greater chance of obtaining a pathological complete response (pCR) after neoadjuvant chemotherapy. In addition, high 21-gene recurrence score (RS) is associated with an increasing rate of pCR in luminal tumors. We investigated the relationship between TIL and RS in 1,883 patients with early ER+HER2- breast cancer. Method: In 1,883 ER+ breast cancer patients with 21-gene assay, TIL level was evaluated. Correlation between continuous TIL and RS was investigated. Logistic-regression analysis was performed to identify risk factors for high RS (26). The cut-off for high TIL was 50%. Recurrence-free survival (RFS) was investigated. Results: A weak positive correlation between TIL level and RS was observed (correlation coefficient=0.283, p< 0.001) in all patients. Average TIL level of the high RS tumors was significantly higher. Two parameters were positively correlated in both two groups classified by age 50 years (correlation coefficient=0.281 in the age 50; correlation coefficient=0.288 in the age>50). Either continuous TILs or binary high TIL level was demonstrated to be an independent factor for high RS. When all patients were divided into 4 groups using TIL and RS (low-RS/low-TIL, low-RS/high-TIL, high-RS/low-TIL, and high-RS/high-TIL), the RFS was worst in the low-TIL/high-RS group (p< 0.001). Conclusions: Our findings show that TIL level is correlated with RS in ER+ breast cancer regardless of age and suggest that high TIL level can be regarded as a risk factor for high RS. Multigene assay could be integrated in designing clinical trials evaluating immune-check point blockades in luminal breast cancer. Recurrence-free survival according to RS and TIL Table 1. 5-years RFS according to TIL and RS Citation Format: Sung Gwe Ahn, Ji Soo Jang, Yoonwon Kook, Seung Ho Baek, Sae Byul Lee, Soong June Bae, Joon Jeong. Tumor-infiltrating lymphocytes (TILs) and 21-gene recurrence score in 1,883 patients with ER+/HER2- breast cancer [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 P6-01-03.