ACUTE PROMYELOCYTIC LEUKEMIA IN THE BRAZILIAN PUBLIC HEALTH SYSTEM: A 25-YEAR SINGLE-CENTER RETROSPECTIVE STUDY

Acute promyelocytic leukemia (APL) is the acute myeloid leukemia subtype with the highest curability when treated with targeted agents such as all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Despite therapeutic advances, early mortality remains a major challenge, particularly in public institutions with limited access to prompt diagnosis and specialized care. Real-world data from public centers are essential to identify gaps in APL management in Brazil. To describe the clinical outcomes of an APL cohort over 25 years. This retrospective study included adults (≥18 years) with genetic confirmation of APL, consecutively admitted from 2000 to 2025 to a single public referral Cancer Center in Rio de Janeiro. The hospital maintains an on-demand ATRA stock for newly admitted patients. Outcomes were overall survival (OS), non- relapse mortality (NRM), and relapse, analyzed using Kaplan–Meier, cumulative incidence, and Cox models. All analyses were performed in R. The local Ethics Committee approved the study. We included 57 patients with a median follow-up of 7.4 years. Fifty-one percent were male. Median age was 37 years; 8 cases were therapy-related. Risk distribution: high (51%), intermediate (35%), low (14%). Thirty-day mortality was 19%, 3.6% in non-high-risk vs. 34,5% in high-risk patients, of which two thirds had hyperleukocytosis above 50.000/mm 3 . The distribution of deaths over the 30-day period was 36,4% ≤3, 18,2% 4-8 and 45,5% 9-30 days. The main cause of death within the first week was bleeding and later, infection. NRM at 6 months was 13%, 32%, and 38% for low-, intermediate-, and high-risk groups, respectively; NRM correlated with age (HR = 1.46 per decade; 95% CI 1.13–1.89; p = 0.004) and secondary APL, with 6-month NRM 75% vs. 25% in de novo APL. Five-year relapse was 8%, independent of risk. Five-year OS was 88%, 62%, and 51% for low-, intermediate-, and high-risk groups. In the last decade, >92% initiated ATRA within 24h vs. 64% in earlier years, without significant reduction in 30-day mortality. Survival and relapse rates were comparable to international ATRA-based data, but secondary APL and high-risk presentations were more frequent. While the former is expected in a Cancer Center, the latter likely reflects referral bias and delayed diagnosis and may be responsible for the high number of patients with hyperleukocytosis. Early mortality remains high, despite despite almost complete coverage of patients receiving ATRA within the first 24 hours of admission in recent years, underscoring the need for improved pre-admission management. NRM during consolidation phases appears to have been influenced by the high incidence of cases related to prior cancer therapy in our cohort and deserves special attention Despite high curability, APL management in the public health system faces structural barriers. Ensuring early diagnosis, rapid referral to experienced centers, as well as intensive supportive care, are critical to reduce mortality and improve outcomes.