Introduction
Acute lymphoblastic leukemia (ALL) is a malignant disease characterized
by an uncontrolled proliferation of immature lymphoid cells.[1] It
is the most common pediatric malignancy and accounting for 20%-30% of
adult acute leukemia. Recently, a distinct patient group named
adolescents and young adults (AYAs; ages 15~39 years) as
defined by the National Cancer Institute (NCI), has received increasing
attention in ALL patients.[2] AYAs diagnosed with ALL differ
considerably from younger children or older adults, who usually face
unique challenges throughout their disease trajectory including
unfavourable biological characteristics, psycho-social problems and
survival disadvantages.[3 4] It is reported that AYAs compared with
pediatric usually experienced worse outcomes with event-free survival
ranging from 57 to 71%, this survival disparity is likely due to
differences in anti-tumor regimens and treatment-related
toxicities.[5] Use of intensive pediatric-inspired regimens in AYA
populations has demonstrated significant improvements in overall
survival (OS).[6] The backbone of pediatric-inspired regimens
includes asparaginase and corticosteroids, both of which are associated
with more toxicity and poor tolerance. Actually, AYAs presented a
greater risk of treatment-related mortality (TRM) than younger
patients.[7] However, few study focused on exploring the influencing
factors of treatment-related mortality (TRM) in AYAs.
With increasing clinical experience, the management and prevention of
infectious complications have emerged as key challenges in ALL. It is
worth noting that the intensified and prolonged use of chemotherapeutic
drugs is usually associated with an increased risk of infections.
Notably, bloodstream infections (BSIs) are still the cardinal infections
throughout the course of chemotherapy in leukemic patients and may lead
to fatality, even if antibacterial/anti-fungal prophylactic regimens
have been administered.[8] A multi-center study performed in China
showed that the treatment-related mortality rate of ALL patients was
2.9%, while infection accounted for 73.4% of the causes of death, and
BSIs accounted for 58.8%.[9] In recent years, significant efforts
have been made to discovering the pathogen distributions and management
of infectious complications in pediatrician and adult ALL patients.[10
11] However, few analyses of the epidemiology, resistance patterns of
bacterial pathogens, and prognostic factors are available for AYAs
diagnosed with ALL. In addition, the potential BSI-related risks factors
in the AYAs population are still pending, and the whole process
management of BSIs of this population inclining to which one remains
unclear. Thus, recognizing and understanding those characteristics of
AYA patients has essential clinical implications for effective cancer
management, patient functioning, and cancer survivor-ship.
Here, we reported the BSI-related event profiles according to age cohort
for ALL patients, explore the epidemiology, resistance patterns of
bacterial pathogens, and prognostic factors of BSIs, and further
compared the similarities and differences between AYAs patients and
other age groups.