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Lymphopenia caused by cranial irradiation in children receiving craniospinal radiotherapy
Insights
Craniospinal irradiation for pediatric posterior fossa tumors significantly reduced lymphocyte counts. While white blood cell counts recovered post-therapy, lymphocyte levels remained low years later, suggesting radiation effects on circulating lymphocytes.
Area of Science:
- Pediatric Oncology
- Radiation Oncology
- Hematology
Background:
- Posterior fossa tumors are a common childhood malignancy requiring craniospinal irradiation.
- Understanding the hematological effects of such treatment is crucial for managing pediatric cancer patients.
Purpose of the Study:
- To investigate the peripheral blood changes in children undergoing craniospinal irradiation for posterior fossa tumors.
- To analyze the impact of cranial and spinal irradiation on leukocyte and lymphocyte counts.
Main Methods:
- Peripheral blood samples were analyzed in 67 children before, during, and after craniospinal irradiation.
- Leukocyte, lymphocyte, and eosinophil counts were measured and compared to preoperative levels.
Main Results:
- Cranial irradiation led to a significant reduction in lymphocyte counts (from 3084/mm3 to 858/mm3).
- Spinal irradiation caused a rapid decrease in all leukocytes, primarily neutropenia.
- Leukocyte counts began to recover post-radiotherapy, but lymphocyte counts remained below preoperative levels even 6 years later.
Conclusions:
- Lymphopenia during cranial radiotherapy is likely due to irradiation of circulating lymphocytes.
- Leukopenia observed with smaller radiation ports may be secondary to lymphopenia, not necessarily indicative of impaired bone marrow reserves.
- Long-term monitoring of lymphocyte counts is important in pediatric patients treated with craniospinal irradiation.
Abstract:
The peripheral blood changes were studied in 67 children who received craniospinal irradiation for posterior fossa tumors. At the completion of a cranial dose of about 3500 rad to the whole brain port, the lymphocytes were reduced to 858/mm3 rom 3084/mm3 preoperatively. The counts of the remaining leukocytes stayed at a level somewhat higher than preoperatively; the eosinophils rose to 288/mm3 from 125/mm3. With the initiation of the spinal field irradiation, which included a large proportion of the total bone marrow, the numbers of all the leukocytes decreased rapidly; the observed leukopenia was mainly secondary to neutropenia. A mechanism that was operating to restore the number of leukocytes became manifest immediately after the completion of radiotherapy, though the number of lymphocytes had not been totally restored to the preoperative level 6 years later. Irradiation of the lymphocytes that circulate through the vascular bed can explain the lymphopenia observed during cranial radiotherapy. Mild leukopenia observed in patients receiving radiotherapy through a relatively small port may be secondary to lymphopenia, and this does not necessarily indicate impaired bone marrow reserves.