Abstract P4-07-08: IMPACT ON OVERALL SURVIVAL ACCORDING TO BREAST CANCER IMMUNOPHENOTYPES: REAL-WORLD DATA IN METASTATIC BREAST CANCER IN ECUADOR
Authors: Valencia-Espinoza Evelyn , Pulla-Cadmilema Emiliano , Avila Lissette P. Velez , Bohorquez Lissette Yagual , del Mar Sanchez Salazar Maria , Aguilar Patricia Tamayo , Martin-Delgado Jimmy , Martinez Glenda Ramos , Matamoros Katherine Garcia , Cornejo Roberto Escala , Merchan Felipe Campoverde , Vivanco Ruth Engracia , Maridueña Mayra Santacruz , Guerrero Isabel Delgado , Floril Veronica Torres , Gamboa Diego Garcia , Rodriguez-Melendez Elina A. 
Published: March 2023

Abstract
Background: Breast cancer immunohistochemistry subtype classification by hormone receptor has become the standard practice for therapeutic decision making. The subtype is one of the crucial factors affecting breast cancer prognostic. Despite the progress in understanding of complex mechanisms in progression of breast cancer, the treatment is a global challenge health around the world, the 5-year survival rate is 26%. Currently in develop countries, in the metastatic stage, a gain in survival in the HR+/HER2+ subtype has been evidenced, likely attributable to major advances in HER2-targeted treatment (1). However, although in developed countries there is access to targeted therapy, in the Ecuadorian health system, difficulties complicate patients access to health care and treatment. Methods: We conducted a retrospective study about survival data in breast cancer metastatic according immunohistochemistry subtype. We analyzed all primary invasive breast cancer cases in the period from 2016 to 2020 in an oncology institute of Ecuador, the final study sample consisted for 83 patients. The 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: There were 31 patients (37.1%) with a HR(+)/HER2(-) breast cancer subtype, 15 patients HR(+)/HER2(+), 5 patients HER2 (+),18 patients HR(-)/HER2(-) and 14 patients without breast cancer subtype identified. Most patients were treated with different chemotherapy protocols; additional, in the group of women with HR(+)/HER2(+) subtype and HER2 (+) subtype only 15.87% were treated with HER2-targeted treatment, the vast majority in the last year. The best survival pattern was observed among women with HR(+)/HER2(-) breast cancer subtype with 35 months (IC 95% = 14,9 – 55), followed by HR(+)/HER2(+) with 27 months (IC 95% = 13,21 – 40,79), HER2 with 24 months (IC 95% = 4.4 – 32), and 14 months (IC 95% = 0 – 29.7) for HR(-)/HER2(-), however the difference wasn’t significant (p = 0.08). Hazard ratio of HR(+)/HER2(-) breast cancer subtype for breast cancer specific mortality risk was 1.61 (IC 95% = 0.64 – 4.19 p = 0.29). Conclusions: Hormone receptor subtype wasn’t s a significant independent prognostic factor in female metastatic breast cancer patients in a single center of Ecuador. However, there is a trend that subtype HR(+)/HER2(-) breast cancer subtype, has a better survival than the rest of the subtypes. These results differ from those of the rest of the world, probably access to target medicine and difficulties in access to health care system are the cause. Thus, better strategies for early access to adequate chemotherapy protocols should be developed
Citation Format: Evelyn Valencia-Espinoza, Emiliano Pulla-Cadmilema, Lissette P. Velez Avila, Lissette Yagual Bohorquez, Maria del Mar Sanchez Salazar, Patricia Tamayo Aguilar, Jimmy Martin-Delgado, Glenda Ramos Martinez, Katherine Garcia Matamoros, Roberto Escala Cornejo, Felipe Campoverde Merchan, Ruth Engracia Vivanco, Mayra Santacruz Maridueña, Isabel Delgado Guerrero, Veronica Torres Floril, Diego Garcia Gamboa, Elina A. Rodriguez-Melendez. IMPACT ON OVERALL SURVIVAL ACCORDING TO BREAST CANCER IMMUNOPHENOTYPES: REAL-WORLD DATA IN METASTATIC BREAST CANCER IN ECUADOR [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 P4-07-08.