Abstract PO1-05-14: Outcomes of first-line chemotherapy for visceral crisis in metastatic breast cancer

Abstract Background: Visceral crisis (VC) in metastatic breast cancer (BC) is defined as severe organ dysfunction, as assessed by signs and symptoms, laboratory tests, and rapid disease progression. The management of this condition is currently based on limited retrospective evidence and expert opinions, since VC has been a common exclusion criterion in clinical trials. There is a paucity of real-world data regarding the management of BC VC. We aim to evaluate the survival outcomes and prognostic factors of first-line palliative chemotherapy for VC in a tertiary cancer center in Brazil. Methods: Data were retrospectively collected from patients with metastatic BC diagnosed with VC between 2017 and 2022 in a single cancer center. Our analysis focused on patients receiving first-line chemotherapy for VC. Patients with hormone receptor-positive BC could have been previously treated with endocrine therapy for metastatic disease. CDK4/6 inhibitors were not available in the cancer center during the study period. Prognostic factors associated with survival were evaluated through univariate and multivariable analyses, using the Cox regression model. Results: A total of 106 patients with VC were evaluated. Among them, 58.5% (62 patients) had not received any previous line of chemotherapy in the metastatic setting before the diagnosis of VC (1st line cohort). Median overall survival (mOS) in the total population was 1.7 months, significantly distinct from the 1st line cohort, which had a mOS of 4.9 months (p < 0.001). Focusing on the 1st line cohort, the most common type of VC was pulmonary (40.3%), followed by hepatic (24.2%), and medullary infiltration (21%). 66.1% of patients had HR+HER2- (mOS 9.3 months), 19.3% HER2+ (mOS 4.5 months), and 11.3% triple-negative BC (TNBC) (mOS 1.5 months). Most patients were treated for VC based on systemic therapy combinations (59.7%), while 32.2% received monochemotherapy, and 8.1% were managed with best supportive care (BSC) alone. In the population receiving multidrug therapy, the mOS was 9.3 months, compared to 4.9 months with monochemotherapy and 0.7 months in patients undergoing BSC. Nevertheless, the type of treatment received was not associated with OS in the multivariable analysis. In the multivariable analysis, the prognostic factors associated with worse mOS were TNBC subtype, hepatic VC), and ECOG-PS > 2. (Table). Among patients with hepatic VC, 73.7% died during the same hospitalization and 60.5% received chemotherapy within 30 days prior to death. Conclusions: Patients with VC due to BC have a poor prognosis, even in the context of first-line chemotherapy. Factors such as ECOG-PS, BC subtype, and VC type should be taken into account when discussing the expected outcomes of this life-threatening condition. Taking these factors into account can help physicians to differentiate patients who are more likely to benefit from systemic oncologic treatment from those for whom such therapy would be futile or potentially harmful. Median overall survival according to baseline characteristics and multivariable analysis (1st line cohort, n=62) Citation Format: Matheus de Oliveira Andrade, Vitor Hugo Felix, Renata Colombo Bonadio, Laura Testa. Outcomes of first-line chemotherapy for visceral crisis in metastatic 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 PO1-05-14.