Page 10 - ARNM-2-1

Advances in Radiotherapy
& Nuclear Medicine Pediatric myelosuppression in radiotherapy

of pediatric oncology patients compared to adult patients. a young adult group (>10 years old) with a boundary of
Literature suggests that strategies for protecting critical 10 years old for further analysis.
organs in children should be differentiated from those
employed for adults. 2-4 2.2. Evaluation of myelosuppression
Red bone marrow is one of the most sensitive tissues The World Health Organization classifies post-
to radiation exposure. A study involving over 1 million radiotherapy adverse events into a grading system using
European children revealed that even a low distribution four indicators: hemoglobin, leukocytes, granulocytes,
of radiation dose (≥10 mGy) to active bone marrow could and platelets (Table 1). In our study, Table 1 was used
elevate relative risks for all hematological malignancies. to grade myelosuppression in pediatric patients, with
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Throughout childhood, the distribution of red bone marrow myelosuppression events defined as grade II or higher
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undergoes significant changes across growth stages. occurrences.
4
Radiation-induced damage to the red bone marrow results 2.3. Statistical methods
in functional inhibition, which manifests as a decrease in
the number of blood cells, leading to anemia and other To reduce the bias in retrospective clinical studies caused
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symptoms. In children, red bone marrow is distributed by differences in baseline covariates among subgroups
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throughout the body and varies with age. However, of patients, the present study used the nearest neighbor
matching algorithm of the MatchIt software package to
the existing guidelines in radiotherapy do not explicitly perform propensity score matching. The data obtained
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consider the distribution of red bone marrow in children using the above methods were statistically analyzed using R
of different ages during protocol optimization.
3.6.1 software. Categorical data were analyzed using Fisher’s
2. Materials and methods exact test, while continuous data were tested using the t-test
for a normal distribution and Wilcoxon’s rank-sum test for a
2.1. Materials non-normal distribution. The significance was set at P < 0.05.
Ethical approval for this retrospective study was obtained 3. Results
from the Institutional Review Board of Peking University
Cancer Hospital and Institute (IRB#2019YJZ76). 3.1. Comparison of myelosuppression in children
Forty-nine pediatric patients (33 males and 16 females) and adults
with a mean age of 11 (range: 5 – 15) years who underwent Myelosuppression was observed in 29 (59.18 %) out of
radiotherapy at our hospital from January 2009 to 49 pediatric patients included in this study. A total of 53% of
December 2019 were retrospectively selected. We utilized patients had leukopenia, 45% had granulocytopenia, and the
the basic architecture of the information aggregation tool incidence of thrombocytopenia and hemoglobinopenia was
reported by Liu et al. to automatically extract and cluster only 10%. Regarding patients with myelosuppression, 66%
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medical record data, such as basic patient information, had leukopenia and granulocytopenia; thrombocytopenia
weekly routine blood examinations during treatment, and hemoglobinopenia were observed in 17.2% of patients.
and other relevant data for subsequent analysis. We In contrast, the incidence of myelosuppression in adult
subgrouped patients based on gender and age to analyze patients reported in the literature was significantly lower,
myelosuppression results and compared them with adult with only 34% of leukopenia of grade II or higher. 10,12
data reported in the literature. The radiotherapy lesion
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sites in the patients enrolled in this study include head and 3.2. Subgroup analysis of pediatric patients
neck (39), chest and abdomen (6), foot (1), femur (1), tibia 3.2.1. Subgrouping according to gender
and fibula (1), and upper limb (1); 37 out of 49 patients
received chemotherapy before or during radiotherapy. The patients were divided according to their gender. As
The prescribed dose to the gross tumor volume (GTV) shown in Table 2, no significant association was observed
ranged from 20 – 70 Gy delivered in 10 – 33 fractions.
The prescribed dose to the clinical tumor volume (CTV) Table 1. Parameters of myelosuppression grade
ranged from 18 – 60 Gy delivered in 10 – 33 fractions. Indicators of Grades
As suggested in the literature, the percentage of red bone toxicity 0 I II III IV
marrow content in the skull of children aged 0 – 10 years Hemoglobin (g/L) ≥110 109 – 95 94 – 80 79 – 65 <65
decreases from 25.3% to 11.6%, whereas the red bone Leucocyte (10 /L) ≥4.0 3.9 – 3.0 2.9 – 2.0 1.9 – 1.0 <1.0
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marrow content in the skull of children aged 10 – 15 years 9
decreases by only 4.3%. Therefore, the pediatric patients Granulocyte (10 /L) ≥2.0 1.9 – 1.5 1.4 – 1.0 0.9 – 0.5 <0.5
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were subdivided into a toddler group (≤10 years old) and Platelet (10 /L) ≥100 99 – 75 74 – 50 49 – 25 <25
Volume 2 Issue 1 (2024) 2 https://doi.org/10.36922/arnm.2519