Page 12 - ARNM-2-1

Advances in Radiotherapy
& Nuclear Medicine Pediatric myelosuppression in radiotherapy

Table 5. Description of baseline data before and after propensity matching according to gender
Variant Before matching After matching P‑value
Male patient Female patient Male patient Female patient
(n=33) (n=16) (n=10) (n=10)
Age (years) 12 (9, 14) 10 (9, 14) 11 (9, 14) 10 (9, 13) 0.71
Prescribed dose (Gy) 30 (22, 56) 40 (23.25, 50) 30 (24, 49) 38 (22.5, 47.5) 0.94
Treatment fraction 15 (11, 28) 20 (12, 25) 15 (12, 24) 19 (11, 24) 0.88
Duration of treatment (days) 17 (14, 35) 27 (14, 31) 19 (15, 32) 28 (15, 32) 0.74
Note: The values are presented as median (quartile ranges).
Table 6. Relationship between sex after propensity matching hemoglobin were less sensitive, consistent with previous
and bone marrow suppression after radiotherapy reports on adult patients. In a study involving 52 pediatric
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patients, the incidence of leukopenia exceeding grade II
Myelosuppression after radiotherapy Male patient Female patient surpassed that of grade II thrombocytopenia (69% vs.
Yes 4 5 5.7%). These data suggest the potential variation in the
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No 6 5 effects of radiotherapy on different hematopoietic cell types.
Myelosuppression is an important factor in the interruption
adult group, while the percentage of thrombocytopenia of and discontinuation of radiotherapy, often resolving after
more than grade III was 8%, which was also higher than treatment cessation; however, in severe cases, patients
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that of 4.7% in the adult group. The higher incidence require prompt clinical intervention, such as recombinant
of radiation-induced myelosuppression in pediatric human granulocyte stimulating factor injection. A report
patients may be related to the following factors: (i) higher on radiation-induced myelosuppression in pediatric patients
radiosensitivity in pediatric patients and (ii) current observed that 69% of the patients developed higher than
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protocol optimization only considers red bone marrow grade II leukopenia, and the number of leukocytes began to
protection when designing radiotherapy plans for the recover on the 5 day after the occurrence of the lowest value;
th
pelvic region, lacking targeted protection for the red bone 5.7% of the patients developed grade II thrombocytopenia;
marrow distributed in the whole body in children, which and the number of platelets began to recover on the 4 day
th
varied with age. after the occurrence of the lowest value. However, the study
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To further investigate the correlation between radiation- did not elaborate on the treatment of pediatric patients after
induced myelosuppression and pediatric patients’ gender the occurrence of myelosuppression. The rate of recovery
and age and to provide more precise evidence for optimizing of routine blood markers with different treatments after
protocols, we analyzed the data in subgroups according to myelosuppression depends on future large-scale prospective
gender and further subdivided patients with a cutoff of randomized controlled trials.
10 years of age but did not observe a significant correlation. Due to the retrospective study design, we were unable
However, another study of 79 children concluded that to investigate the volume and dose of red bone marrow.
children younger than 6 years old were significantly more The bone marrow was not segmented during the treatment
likely to develop thrombocytopenia (29% vs. 8.7%) and planning stage, and the dose to the bone marrow was not
were twice as likely to develop neutropenia as children optimized. One challenge in segmenting the bone marrow
older than 6 years old (41% vs. 21%). This may be related from the cancellous bone was the relatively large spatial
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to the small sample size of our study. In addition, the resolution of the planning CT images, making this process
red bone marrow content in the head-and-neck region time-consuming and clinically concerning. Therefore,
declined rapidly in children aged 0 to 10 years, and the according to literature, the dose to the bone marrow is
ratio of red bone marrow in the head-and-neck region to usually approximated using the dose to the bone or
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whole-body red bone content gradually decreased after the estimated from the total dose. Moreover, the medical
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age of 10. records of some patients could not be fully retrieved to
Our study revealed that leukopenia and granulocytopenia study the impact of chemotherapy, as they were treated
were the most sensitive indicators of myelosuppression in at other hospitals before undergoing radiotherapy at our
pediatric patients (53% and 45%, respectively) and that institution. These limitations require further investigations
66% of patients with myelosuppression experienced both in the future based on a more reliable prospective and
leukopenia and granulocytopenia. In contrast, platelets and randomized study design with a larger patient volume.

Volume 2 Issue 1 (2024) 4 https://doi.org/10.36922/arnm.2519