Navigating neutropenia in oncology: Insights into clinical characteristics and outcomes from a Brazilian clinic.

e24090 Background: Neutropenia is a frequent adverse event associated with antineoplastic agents, yet real-world data during the COVID pandemic remains scarce. This study evaluated neutropenia-related adverse drug reactions (ADRs) to identify factors influencing severity and outcomes, aiming to improve clinical safety. Methods: We retrospectively analyzed data from a Brazilian oncology clinic (2019–2021) on patients with grade III/IV neutropenia treated with parenteral oncology protocols and/or CDK inhibitors. Oral chemotherapy (CT) was excluded due to traceability challenges. Diseases were classified using ICD codes, toxicities graded per CTCAE 5.0, and ADR causality determined via the Naranjo algorithm. Statistical analyses included Mann-Whitney, chi-square, Fisher’s exact test, and univariate logistic regression to analyze factors associated with neutropenia grade and outcomes. Results: Among 238 neutropenia events in 131 patients, 74% occurred in women, 47% in patients under 65 years, and 5.9% were febrile neutropenia. There were 1.8 events per patient. Solid tumors comprised 71% of cases (70% breast cancer, 8.8% male genitourinary, 6.5% female genital), while 29% were hematological malignancies. Solid tumors were more frequent in younger patients (median age: 60 vs. 70). Platinum doublets predominated in solid tumors (38%), while R-based regimens were common in hematological malignancies. Causality analysis identified 19.3% as definite (12% hematological vs. 22% solid), 69.3% as probable, and 11.4% as possible. Treatment deferral was the predominant management (61%). Deferral+G-CSF was used in 6.3% (7.6% solid vs. 2.9% hematological) and hospitalization+G-CSF in 4.2% (5.3% vs. 1.5%). Therapy continuation was more frequent in hematological malignancies (31% vs. 14%). Recovery occurred in 68%, with patients < 65y (OR 2.60; p < 0.01) and those with solid tumors (OR 7.61; p < 0.01) achieving better outcomes. Grade IV neutropenia was less frequent in solid tumors (OR 0.41; p < 0.01) and breast cancers (OR 0.37; p < 0.05). Mono-CT regimens were linked to lower recovery rates (OR 0.45; p < 0.01), likely due to older age in this group (median 68 vs. 60 y). Conclusions: This study highlights the influence of age, tumor type, and chemotherapy regimen on neutropenia during the COVID-19 pandemic, with better recovery in younger patients and solid tumors. The predominance of female patients reflects the clinic's higher percentage of breast cancer cases, while lower rates of grade IV neutropenia demonstrate the team's expertise in safety measures like growth factors. Slower recovery in older patients, even with mono-CT, underscores the need for tools such as FENCE, CARG-toxicity, CRASH, and Charlson Comorbidity Index to assess vulnerabilities and guide tailored treatment strategies that balance efficacy, reduce ADRs, and improve outcomes for older adults on systemic therapy.