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.