Abstract PO2-10-04: Clinicopathological Characteristics and Factors Associated With Screening and Late-Stage Diagnosis in Patients With Breast Cancer in Latin America: The LATINA Study (LACOG 0615/MO39485)

Abstract Background: Breast cancer (BC) is the most common malignancy and one of the leading causes of cancer death in women in Latin America (LATAM). However, the region lacks a unified multinational initiative to investigate BC and to further understand regional disparities. Methods: LATINA (LACOG 0615/MO39485) is the first multinational prospective cohort study designed to describe clinicopathological characteristics, treatment patterns, and outcomes of patients with BC in LATAM. Patients aged ≥18 years diagnosed with primary or recurrent BC in the 12 months preceding site activation were included. Data were collected at enrollment and every 6 months for up to 5 years. We present here the results for clinicopathological and demographic characteristics at BC diagnosis. Multivariable logistic regression was performed to investigate characteristics associated with later diagnosis (stage II/III vs. stage I) and detection method (symptomatic vs. screening). Causal mediation analysis was performed to investigate the detection method as a mediator of the effect of health care provision (public or private) on stage at diagnosis. Results: Between February 2020 and August 2022, 3276 patients from 31 research sites in 10 LATAM countries were included. Most patients in this cohort (72.1%, N=2362) were treated in the public health system. Regarding ethnicity, most patients (91.8%, N=3008) self-identified as Latinos and were White (47.3%, N=1549), American Indian (21.0%, N=689), and Black or Brown (16.6%, N=544). The median age at diagnosis was 54 years (range 23–95), 41.8% (N=1368) were < 50 years of age at BC diagnosis, and 54.1% (N=375) of the American Indian patients were ≤50 years of age. BC subtype distribution was: 43.2% (N=1336) luminal A, 14.3% (N=433) luminal B, 22.9% (N=709) human epidermal growth factor receptor 2-positive (HER2+), and 15.4% (N=477) triple negative. In patients older than 50 years old, most cases were detected with symptoms, particularly in the public health system (63.2%, N=836) vs. 50.5% (N=232) in the private health system, p< 0.0001). This was also the case in Black/Brown (61.6%, N=178) and American Indian patients (89.5%, N=281) vs. White patients (45.6%, N=413) (p< 0.0001). In the public system, 37.7% (N=890) and 31.7% (N=748) of cases were diagnosed at stage II and III vs. 37.6% (N=343) and 26.6% (N=243) of cases in the private system, respectively (p< 0.0001). Users of the public health system had a significantly higher risk of being diagnosed with symptoms vs. screening (adjusted odds ratio [aOR] 3.54, 95% CI 2.17–5.76). Causal mediation analysis showed that the detection method (screening vs. symptomatic) mediated 21.8% (95% CI 1.7%–41.9%, p=0.034) of the effect of health care provision (public or private) on stage at diagnosis. Self-identifying as Black (aOR 2.11, 95% CI 1.29–3.45), age < 40 years (aOR 1.97, 95% CI 1.20–3.23), public health care provision (aOR 2.18, 95% CI 1.32–3.59), and a diagnosis of HER2+ (aOR 1.74, 95% CI 1.20–2.52) or triple-negative BC (aOR 2.34, 95% CI 1.47–3.71) were associated with an increased risk of being diagnosed at a later stage. Conclusions: A significant proportion of new BC diagnoses in LATAM is observed in patients < 50 years of age. Reflecting the low screening coverage throughout the region, most patients detect the disease with symptoms. Stage III BC accounted for 30.3% of new cases, being more common among users of the public health system. Differences in the stage at diagnosis related to health care provision (public or private), ethnicity, and country underscore significant disparities that need to be addressed. Further analyses of these data will help identify factors associated with late diagnosis and support the development of regional corrective health policies. Citation Format: Gustavo Werutsky, Cynthia Villarreal-Garza, Henry Gómez, Juan Manuel Donaire, José Bines, Luis Henrique Fein, Maria Clara Horsburgh, Paula Cabrera-Galeana, Heloísa Resende, Rosa Vasallo Veras, Miriam Raimondo, Ricardo Elías Brugés Maya, Vidal Maria Del Rosario, Yeni Nerón, Ana Maria Donoso, Fernanda B. Damian, José D'Oliveira, Couto Filho, Maria Isabel Alonso, Victoria Costanzo, Tomás Reinert, Adriana Elizabeth Borello, Eduardo Cronenberger, Luis Fein, Marcela Urrego, Enrique Alanya, Jorge Luis Soriano García, Saúl Campos-Gomez, Eduardo A. Richardet, Hugo Castro-Salguero, Felipe Cruz, Diego Gómez, Angel Hernández, Carlos Alberto Farfan Tello, Ronald Rodríguez, Rafaela Jesus, Gustavo Gössling, Carlos Barrios. Clinicopathological Characteristics and Factors Associated With Screening and Late-Stage Diagnosis in Patients With Breast Cancer in Latin America: The LATINA Study (LACOG 0615/MO39485) [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 PO2-10-04.