Abstract PS04-01: Clinical impact of timing of systemic therapy in patients with early triple negative breast cancer

Abstract Introduction TNBC is known for its aggressive nature, with early recurrence and limited treatment options beyond chemotherapy and recently immunotherapy. We aim to clarify, whether timing of systemic therapy has an impact on survival in patients with early TNBC. Methods Data from a large population-based regional cancer registry covering over 2.2 million people was used for evaluation, including women with diagnoses of TNBC between 2010 and 2018. Patients were categorized into subgroups according to the interval from TNBC pathologic diagnosis to the date of first administration of NACT (TTNC) or according to the interval from primary surgery to the date of first administration of adjuvant chemotherapy (TTAC). Univariable analyses of survival rates were conducted using the Kaplan-Meier method, the log-rank test was used for group comparisons. IBM SPSS Statistic 25 was used to perform statistical analysis, with hazard ratios, p-values, and 95% confidence intervals calculated for each model. All tests were two-sided, and significance was set at p < .05. Results We identified 37 382 patients with malignant neoplasms of the mammary gland. The final study cohort included 732 patients with early TNBC, of whom 43.6% were treated with NACT and 40.3% with adjuvant chemotherapy. Timing of NACT 270 patients with TNBC treated with NACT had a valid TTNC. Median follow up was 3.5 years. Patients with TTNC ≤14, ≤42, >42, and >56 days had estimated mean OS of 8.4, 6.9, 4.6, and 3.3 years, respectively. Patients with a TTNC ≤14 days were more likely to survive than patients with a TTNC ≥ 56 days (p= 0.054). Significance was barely not reached in the group of NACT. Timing of adjuvant chemotherapy 245 patients with TNBC treated with adjuvant chemotherapy had a valid TTAC. Treatment given within 22-28 days led to the best outcome with a mean OS of 10.2 years, while later treatment (29-35, 36-42 days, or >6 weeks) had significant reduced mean OS of 8.3, 7.8, and 6.9 years. Patients who received therapy within 22-28 days had significantly better survival than those who received therapy between 29-35 days (p=0.043) or after more than 43 days (p=0.033). Conclusion Although significance was barely not reached in the subgroup of patients treated with NACT, the results in this large population-based study indicate that there are critical time intervals for initiation of systemic therapy in patients with early TNBC, with reduced OS if NACT is applied later than 42 days after diagnosis or if adjuvant chemotherapy is applied later than 42 days after surgery. We recommend not to exceed the 6-week interval until the initiation of systemic therapy in patients with early TNBC. Citation Format: Maria Eleni Hatzipanagiotou, Miriam Pigerl, Michael Gerken, Sophie Räpple, Verena Zeltner, Madeleine Hetterich, Elisabeth C. Inwald, Monika Klinkhammer-Schalke, Olaf Ortmann, Stephan Seitz. Clinical impact of timing of systemic therapy in patients with early triple negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS04-01.