Treatment patterns and survival outcomes in metastatic castration-resistant prostate cancer in the Brazilian population: LACOG 1818.

27 Background: Prostate cancer is the second leading cause of cancer death in men worldwide. In Brazil, 75% of patients (pts) rely on the public healthcare system, where access to novel therapies is limited. This disparity may lead to significant differences in survival outcomes. The LACOG 1818 study aims to address this gap by evaluating survival outcomes and treatment patterns among Brazilian pts diagnosed with metastatic castration resistant prostate cancer (mCRPC) in different healthcare settings (public versus private). Methods: LACOG 1818 is a retrospective cohort that included Brazilian pts from 18 research sites diagnosed with mCRPC between Jan 2014 and Dec 2017. Data on pts demographics, clinicopathological features, treatment patterns, and overall survival (OS) were collected from medical records. The primary endpoint was cause-specific survival (CSS) estimated by Kaplan-Meier method. Comparisons between groups (public vs. private healthcare) were assessed by chi-square and the log-rank tests. Results: From Jan 2020 to Jan 2022, 582 eligible pts were included. The median age was 49 (26-53) years, 259 (45%) were white and 85 (15%) were black/brown. Most had bone metastases (n=499, 86%), followed by non-regional lymph-nodes (n=239, 41%). A total of 323 (55%) pts had public and 259 (45%) had private health coverage. The main modality of castration was biochemical castration (n=442, 76% [public 60% vs. private 96%; p<0.0001]), followed by bilateral orchiectomy (n=140, 24% [public 40% vs. private 4%; p<0.0001]). 499 pts had available data on systemic treatment for mCRPC: 473 (95%) received first line; 247 (49%) second line; and 147 (29%) ≥ 3 lines. 378 (65%) pts received a bone protector agent (63% in public vs. 68% in private; p <0.001). At median follow-up of 59 months (95% CI 54.3-62.1), median OS was 57.1 months (95% CI 47.0-65.2) in overall sample; 44.8 months (95% CI 36.0-57.1) in public versus 65.7 months (95% CI 59.8-79.1) in private (HR 1.4 [95%IC 1.1-1.8] p=0.0051). The median CSS was 73.8 months (95% CI 55.1.-NR) in public versus 102.4 months (95% CI 83.4-102.4) in private (HR 1.9 [95%IC 1.4-2.6] p<0.0001). Conclusions: LACOG 1818 study demonstrated significant disparities in treatment patterns and survival outcomes between public and private settings for Brazilian pts with mCRPC. Pts with private coverage had longer OS and CSS. These findings underscore the need for improved access to novel therapies and comprehensive cancer care in Brazil's public healthcare system to reduce survival disparities. Clinical trial information: NCT04962919 . Private Public P First-line N=221 N= 251 <0.0001 ARPI 132 (60%) 18 (7%) Antiandrogen 30 (13%) 127(51%) Chemotherapy 59 (27%) 106 (42%) Second-line N=132 N=110 <0.0001 ARPI 75 (57%) 25 (23%) Antiandrogen 5 (4%) 22 (20%) Chemotherapy 52 (39%) 63 (57%) ARPI= Antiandrogen receptor pathways inhibitor. Antiandrogen= bicalutamide, flutamide, cyproterone and DES.