WBC white blood cell

Abstract

Background. Adolescents/young adults (AYAs) with acute lymphoblastic leukemia (ALL) are more likely to have chemotherapy-related complications than children. In addition, several reports have shown that infections account for most of the therapy-related mortality during cancer treatment in AYAs. Thus, we hypothesized that chemotherapy-induced myelosuppression is more severe in AYAs than in children, and the state of neutropenia was compared between children and AYAs using the D-index, a numerical value calculated from the duration and depth of neutropenia. Procedure. This study retrospectively analyzed 95 patients newly diagnosed with ALL at our institution between 2007 and 2019. Of these, 81 were children (< 15 years old) and 14 were AYAs (≥ 15 years old). The D-index and duration of neutropenia during induction chemotherapy for ALL were compared between children and AYAs. Results. The median D-index of children was significantly higher than that of AYAs (8,187 vs. 6,446, respectively,P = 0.017). Moreover, the median duration of neutropenia was also significantly longer in children than in AYAs (24.0 days vs. 11.5 days, respectively, P = 0.007). Conclusion. Contrary to our expectations, myelosuppressive toxicity during induction chemotherapy for ALL was more severe in children than in AYAs.
Key words: acute lymphoblastic leukemia, adolescents and young adults, chemotherapy, D-index, myelosuppression.
Introduction
Clinical outcomes of treatment for acute lymphoblastic leukemia (ALL) in children have greatly improved over the past decades due to the identification of effective methods for administration of chemotherapeutic agents, the introduction of risk-stratified protocols, and the development of supportive care [1-3]. The use of a pediatric protocol for the treatment of adolescents/young adults (AYAs) with ALL has proven to be more effective than the regimen used for adult patients with ALL [4-5]. However, it has been suggested that applying a pediatric protocol for ALL to AYAs can lead to an increased rate of therapy-related toxicities [6-7]. In addition, several studies have demonstrated that AYAs exhibit higher morbidity than children during treatment for ALL, and some reports have shown that infections account for the majority of therapy-related mortality (TRM) in AYAs [8-13]. Furthermore, the incidence of invasive fungal infection (IFI) during cancer chemotherapy is higher in AYAs than in children [14-16]. A possible explanation for these issues is the difference in chemotherapy-induced myelotoxicity between children and AYAs. Thus, we aimed to test this hypothesis in the present study.
To accurately determine the intensity of myelosuppression, a numerical value called the D-index, which is based on the duration and depth of neutropenia, was employed. The D-index was developed as a tool to predict the risk of invasive fungal infections (IFI), and showed better performance than simply utilizing the duration of neutropenia as a predictor of IFI [17,18]. Further, it is easily calculated using only the absolute neutrophil counts during chemotherapy. Therefore, the D-index is considered to be a useful and effective clinical parameter to assess myelosuppressive toxicity.