Abstract P2-11-21: Outcomes and Treatment Pattern in Women With 1 cm or Smaller, Node-Negative Hormone Receptor-negative Breast Cancer in Fudan University Shanghai Cancer Center

Abstract

Abstract Background: To evaluate the outcome the treatment pattern in women diagnosed with T1mic, T1a and T1b, node-negative, hormone receptor (HR) –negative breast cancer. Methods: This was a retrospective cohort study within the Fudan University Shanghai Cancer Center (FUSCC) that included 605 women with T1mic,a,bN0M0 breast cancer treated between 2010 and 2020. Tumors were grouped by size (T1mic, T1a, T1b), biologic subtype defined by hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status, and receipt of chemotherapy with or without trastuzumab. Kaplan-Meier product was used to calculate invasive disease-free survival (iDFS), breast cancer-specific survival (BCSS) and overall survival (OS). Results: Median follow-up time was 5.0 years. Seventy-three percent of patients with triple-negative breast cancer (TNBC) were treated with chemotherapy. For those with HER2- positive breast cancers, 82% received chemotherapy, and 71% received trastuzumab. The treatment pattern varied over the years, with a downward trend of chemotherapy in TNBC and an upward trend of trastuzumab in HER2-positive breast cancer. Survival outcomes diverged by subtype and size. In this retrospective cohort study, the 5-year DFS for treated patients with T1mic,a tumors ranged from 96.2% to 97.7%, and for patients with T1b tumors, it ranged from 92.1% to 95.0%. The 5-year DFS for patients with T1mic,a tumors untreated with chemotherapy or trastuzumab was 100%. The 5-year DFS for TNBC patients with T1b tumors untreated with chemotherapy was 90.5%, while for HER2-positive patients with T1b tumors untreated with chemotherapy or trastuzumab it was 87.5%, Conclusion: Women with T1mic,a tumors have an excellent prognosis without chemotherapy or trastuzumab, representing an optimal group for evaluating less toxic adjuvant regimens to maintain efficacy while minimizing short- and long-term risks. Figure 1 Systematic Treatment Pattern of Patients With T1mic, a, b N0 Patients With Triple-negative or HER2-positive Breast Cancer from 2010 to 2020 Figure 1 Systematic Treatment Pattern of Patients With T1mic, a, b N0 Patients With Triple-negative or HER2-positive Breast Cancer from 2010 to 2020 Table 1. Patient Demographics and Clinicopathologic Characteristics for T1mic, a, b N0 Patients With Triple-negative or HER2-positive Breast Cancer, FUSCC 2010-2020 Table 2 Systematic Treatment of Patients With T1mic, a, b N0 Patients With Triple-negative or HER2-positive Breast Cancer, FUSCC 2010-2020 Citation Format: Xiyu Liu, Min He. Outcomes and Treatment Pattern in Women With 1 cm or Smaller, Node-Negative Hormone Receptor-negative Breast Cancer in Fudan University Shanghai Cancer Center [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 P2-11-21.