Abstract P4-07-07: Impact on overall survival according to sites of metastasis: Real-world data
Authors: Bohorquez Lissette Yagual , Valencia-Espinoza Evelyn , Pulla-Cadmilema Emiliano , Avila Lissette P. Velez , del Mar Sanchez Salazar Maria , Aguilar Patricia Tamayo , Martin-Delgado Jimmy , Martinez Glenda Ramos , Matamoros Katherine Garcia , Merchan Felipe Campoverde , Vivanco Ruth Engracia , Maridueña Mayra Santacruz , Cornejo Roberto Escala , Guerrero Isabel Delgado , Floril Veronica Torres , Gamboa Diego Garcia , Rodriguez-Melendez Elina A. 
Published: March 2023

Abstract
Background Metastatic breast cancer, has a heterogeneous presentation and management, therefore its overall survival ranges from 2 to 3 years. Despite advances in breast cancer screening, diagnosis, and treatment, nearly 12-30% of early stage breast cancer patients eventually develop metastatic disease. In Ecuador, breast cancer is the most common malignancy among women, and the leading cause of newly diagnose cancer in the general population (Globocan 2020). This study aims to determine the frequency of metastatic sites and its impact in overall survival. Methods: An observational, retrospective, descriptive, single-center study was carried out. All patients with Metastatic breast cancer who had been treated at the National Oncology Institute SOLCA Guayaquil, in the period from 2016 to 2020 were included in the analysis. All statistical analyses were performed using SPSS for Windows (version 25.0;SPSS). The Kolmogorov-Smirnov test was used to test for the normality of distribution. Correlations were determined with Spearman correlation coefficients. The number of metastatic sites were recorded and their impact on overall survival was calculated by the Kaplan-Meier method and compared by the long-rank test, multivariable adjusted hazard ratios (HR) were estimated by Cox regression models. Results: A total of 1113 patients were included in the analysis, of which 84 patients (7.5%) were metastatic disease. The distribution of metastatic sites at diagnosis were: bone 64% (n=53), lung 51% (n=42), liver 30% (n=25), soft tissues 23% (n=19), and the least frequent were metastases to the central nervous system 17% (n=14), mediastinal lymph node 5% (n=4), peritoneal lymph node 1% (n=1). Regarding metastatic sites, 41% (N: 35) had only 1 metastatic site, 33,7% (N: 28) had 2 metastatic sites, and 25.3% (N:21) has 3 or more sites. A multivariable analysis was performed which takes into account all the metastases in the analysis. All have a higher risk of mortality vs not having any metastasis (all are greater than 1). But the only significant one is CNS with a RR 1,31 (1,08 - 1,61) P=0,005. Three or more sites of metastasis have RR 1,22 (0.95-1.57) p: 0.11. Relative Risk (RR) according to the different sites of metastasis are shown in the table#1. The association between 3 or more sites of metastasis showed a negative impact on overall survival (15 months +/-2.3 SD vs 36 months +/- 3.7 SD) compared to 1 site of metastasis. Conclusions: Approximately half of the women (N:49) with metastatic breast cancer in our population presented 2 or more sites of metastasis, which significantly decreases overall survival. The central nervous system is the site of metastasis with the highest relative risk of mortality, generating functional deterioration, adding morbidity, and only 64% (9 out of 14) of the patients access to radiotherapy as palliative treatment. Thus, better strategies for early diagnosis and adequate treatment of metastatic disease should be developed.
Citation Format: Lissette Yagual Bohorquez, Evelyn Valencia-Espinoza, Emiliano Pulla-Cadmilema, Lissette P. Velez Avila, Maria del Mar Sanchez Salazar, Patricia Tamayo Aguilar, Jimmy Martin-Delgado, Glenda Ramos Martinez, Katherine Garcia Matamoros, Felipe Campoverde Merchan, Ruth Engracia Vivanco, Mayra Santacruz Maridueña, Roberto Escala Cornejo, Isabel Delgado Guerrero, Veronica Torres Floril, Diego Garcia Gamboa, Elina A. Rodriguez-Melendez. Impact on overall survival according to sites of metastasis: Real-world data [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 P4-07-07.