Abstract P3-03-19: Real-world data of clinical characteristics, risk factors and outcomes of Chilean triple-negative breast cancer patients
Authors: Walbaum Benjamin , ACEVEDO FRANCISCO , Bauerle Catherine , Camus Mauricio , Manzor Manuel , Martinez Raul , Veglia Paulina , Navarro Marisel , Guerra Constanza , Dominguez Francisco , Merino Tomas , Medina Lidia , SÁNCHEZ CÉSAR 
Published: March 2023

Background: triple-negative breast cancer (TNBC) is associated with hereditary and environmental risk factors plus an overall worse prognosis compared to other Breast Cancer (BC) subtypes. While TNBC risk factors, prevalence, clinical characteristics and prognosis may vary throughout different populations, limited data on Latin American patients forces clinical decisions to be based predominantly on data coming from non-Hispanic women. To obtain local epidemiological information, regarding risk factors and clinical outcomes, we analysed the largest Chilean BC registry.

Methods: we conducted a retrospective population-cohort study involving females with any stage TNBC, treated at a community hospital (mid-low income) and at an academic private hospital (high income), between the years 2010 and 2021. Risk factors, reason for consultation, clinical and pathological characteristics and prognosis were separately analysed for both TNBC and non-TNBC subgroups. Univariate and multivariate analyses were performed to identify prognostic factors for survival on TNBC patients.

Results: From 5,806 patients, 647 (11.2%) were identified as TNBC. Compared to non-TNBC patients, women were younger (median age 55.2 vs. 57.2, p=0.0001), with 15.8% of TNBC patients having been diagnosed before the age of 40 compared to 9.6% in non-TNBC (p= 0.0001). TNBC had a significantly lower screen-detected cancer rate (14.5% vs. 31.6% p= 0.0001) and worse stage at diagnosis. No differences were seen between patients seen at a community hospital and private centre, for both TNBC rate and stage. Other risk factors such as parity, age at first gestation, menarche, hormone therapy replacement and obesity showed no significant differences between TNBC and no-TNBC patients (table 1). With a median follow up of 57 months, 5-year overall survival (OS) and BC specific death were significantly shorter for TNBC compared to non-TNBC (76.4% vs 88.1% and 78.9% vs 91.2%, respectively; p=0.0001) (table 2). In the multivariate analysis, TN subtype (HR=2.3, p=0.0001), stage (HR=2.05 for stage II vs stage I, HR=7.04 for stage III vs. stage I, p=0.0001), lower income (HR= 1.64, p=0.0001), and non-screened detected BC (HR=1.32, p=0.03) were all associated with worse overall survival (table 3).

Conclusion: This is the first study focusing on TNBC characteristics in Chilean BC patients and to our knowledge, the largest performed in a Latin American population. We identified a lower proportion of TNBC patients when compared with data reported from other LA groups and worldwide, a very low screen detected cancer rate and as expected significantly lower TNBC survival rate compared to non-TNBC women. While TNBC patients were younger compared to the non-TNBC group, this age difference was marginal compared to other reported studies. Community hospital patients (with mid-low income) were associated with lower survival rates for both all-cause mortality and BC specific survival, regardless of a similar stage distribution at diagnosis. Reflecting an underlying interaction between social and biological factors that needs to be addressed.

Table 1. Patient characteristics: Triple-negative versus noN-triple negative breast cancer BMI: Body mass index; FH: Family history * Difference is statistically significant.

Table 2. Survival comparison in triple-negative versus non-triple negative breast cancer * Difference is statistically significant.

Table 3. Cox Regression Multivariate analysis * Difference is statistically significant.

Citation Format: Benjamin Walbaum, FRANCISCO ACEVEDO, Catherine Bauerle, Mauricio Camus, Manuel Manzor, Raul Martinez, Paulina Veglia, Marisel Navarro, Constanza Guerra, Francisco Dominguez, Tomas Merino, Lidia Medina, CÉSAR SÁNCHEZ. Real-world data of clinical characteristics, risk factors and outcomes of Chilean triple-negative breast cancer patients [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 P3-03-19.