Abstract PS8-36: Why is neoadjuvant treatment for patients with triple negative breast cancer of T1cN0 required ?
Authors: Choi Hyang Suk , Cho In-Jeong , Noh Hany , Kim Kwang-Min , Nam Kyoung Tae , Han Airi 
Published: February 2021

Background) Patients with early stage triple negative breast cancer(TNBC) are typically treated with surgery and chemotherapy, and sometimes radiotherapy. Despite effective neoadjuvant and adjuvant chemotherapies, the relapse rate is high and up to 50% of patients will experience disease recurrence including 10% of patients with stage I disease, and pCR is useful surrogate marker for patients with neoadjuvant treatment. Currently Neoadjuvant treatment is recommended for patients with TNBC of 2cm or larger at diagnosis. However, patients with T1 disease at diagnosis are mostly recommended with upfront surgery because uncertain clinical meaning of pCR and potential escalation of treatment for patients with non-pCR in this group. The aim of this study is to see whether patients with T1c of TNBC has different prognosis from T1a /b of same or different subtype and the potential benefit of neoadjuvant treatment exist or not. Material and methods) From 2000 to 2015, female patients treated with upfront surgery for stage I-III breast cancer were included. Patients of estrogen receptor positive disease and TNBC were further stratified according to the tumor size. The primary objective of this study was to see the different incidence of disease recurrence, for which chi-square test or Fisher’s exact tests were used. The secondary objective was recurrence free survival and distant disease free survival, for which Kaplan-Meier(K-M) graphs were generated and compared with log-rank test. Results) None of the TNBC patients experienced disease recurrence when they have T1a/b disease. However, patients with T1c disease showed similar incidence of disease recurrence with patients with T2 or T3 stage (89% vs. 86%), suggesting conventional T staging might not reflect real characteristics of TNBC. On the other hands, patients with ER positive disease less affected by tumor size, showing incidence of recurrent disease of T1a/b, T1c and T2 or over as 96.7%, 93.1% and 91.5% respectively. K-M graphs were generated and log-rank test showed worse survival of patients with T1c of TNBC than T1a/b and rather similar prognosis with patients with T2 or over. Conclusion) Effective adjuvant treatment, such as capecitabine had been proposed for patients with non-pCR. However, mixed results are reported, suggesting appropriate selection of patients is critical. While we need to define TNBC better, patients also need appropriate biomarker to decide whether they need escalated treatment after completion of neoadjuvant treatment. Given the dismal prognosis of T1c of TNBC, we propose this group of patients might benefit from preoperative systemic treatment with using pathologic result as surrogate marker.

Citation Format: Hyang Suk Choi, In-Jeong Cho, Hany Noh, Kwang-Min Kim, Kyoung Tae Nam, Airi Han. Why is neoadjuvant treatment for patients with triple negative breast cancer of T1cN0 required ? [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 PS8-36.