Arslan, SueleymanBerber, IlhamiKuku, IrfanKaya, EminErkurt, Mehmet AliBicim, SoykanKaya, Ahmet2026-04-042026-04-0420251473-05021878-1683https://doi.org/10.1016/j.transci.2025.104171https://hdl.handle.net/11616/109405Background: Granulocyte colony-stimulating factor (G-CSF) is routinely administered following autologous stem cell transplantation in patients with multiple myeloma (MM); however, the optimal timing for its initiation remains unclear. While previous studies have evaluated heterogeneous patient cohorts, including those with MM, Non-Hodgkin's Lymphoma, and Hodgkin's Lymphoma, this study focuses exclusively on MM patients. We aimed to compare the outcomes of initiating G-CSF either on day + 1 post-transplantation or upon the onset of neutropenia, with particular emphasis on neutrophil and platelet engraftment times, to help define an optimal G-CSF administration strategy in this patient population. Study design and methods: This retrospective study included 122 MM patients who underwent autologous hematopoietic stem cell transplantation between 2016 and 2022 at the Hematology Clinic of & Idot;n & ouml;n & uuml; University Turgut & Ouml;zal Medical Center. Patients were evenly divided into two groups. In Group 1, filgrastim was initiated on day + 1 post-transplantation, while in Group 2, it was administered after the onset of neutropenia. Neutrophil and platelet engraftment times, as well as antibiotic usage, were compared between the groups. Results: There were no statistically significant differences in neutrophil or platelet engraftment times or in antibiotic usage between the two groups (p > 0.05). The median neutrophil and platelet engraftment times were 14 and 15 days, respectively, in the day + 1 group, and 15 and 14 days in the neutropenia-guided group. However, the median number of filgrastim injections was significantly lower in the neutropenia group (8 injections, range: 6-12) compared to the day + 1 group (14 injections, range: 8-24) (p < 0.001). Conclusion: Initiating G-CSF upon the development of neutropenia is as effective as early (day +1) administration in MM patients undergoing autologous transplantation. This delayed strategy does not adversely affect engraftment or antibiotic requirements and significantly reduces the number of G-CSF injections, offering potential benefits in terms of cost-effectiveness and reduced side effects.eninfo:eu-repo/semantics/closedAccessAutologous hematopoietic stem celltransplantationFilgrastimEngraftmentMultiple myelomaArticle6444051350210.1016/j.transci.2025.1041712-s2.0-105007657176Q3WOS:001511147400001Q40000-0001-8605-84970000-0003-3312-84760000-0002-3285-417X