Comparison of Initial Absolute Monocyte Counts in 7-Day Recovery vs Nonrecovery Neutrophil Counts After Chemotherapy in Patients With Solid Organ Malignancy

Background: Neutropenia following chemotherapy is a common side effect that often delays treatment cycles, potentially affecting therapeutic outcomes in patients with cancer. Studies suggest that baseline monocyte count may predict neutrophil recovery after chemotherapy, aiding in better treatment planning. Objective: To investigate the association between the initial monocyte count on the day of neutropenia and neutrophil recovery on day 7. Patients were categorized into 2 groups: recovery (absolute neutrophil count [ANC] ≥ 1500 cells/µL) and nonrecovery (ANC < 1500 cells/µL). Methods: A retrospective cohort study was conducted at Chonburi Hospital, and the records of patients with solid organ malignancy who received chemotherapy from 1 January 2022 to 31 August 2023, were analyzed. Patients with neutropenia on chemotherapy day were included in the study. The initial monocyte count was compared between patients who recovered on day 7 and those who did not. Predictive power was assessed using the area under the receiver operating characteristic curve (AUROC). Results: Of 42 patients, 29 (69.04%) achieved neutrophil recovery. The initial monocyte count was significantly higher in the recovery group than in the nonrecovery group (mean [SD], 422.97 [144.66] vs 272.00 [82.13] cells/µL; P = .001). An initial monocyte count of ≥ 375 cells/µL was identified as a predictive threshold for recovery, with an AUROC of 0.803, sensitivity of 58.6%, and specificity of 100%. Conclusions: The initial monocyte count significantly differs between patients who recover and those who do not. A threshold of ≥ 375 cells/µL accurately predicts neutrophil recovery on day 7, potentially optimizing chemotherapy scheduling.