Professor Zhu Xiling: What are the Side Effects of Radiotherapy? Will it Affect Children's Intelligence and Height?

Professor Zhu Xiling: What are the Side Effects of Radiotherapy? Will it Affect Children's Intelligence and Height?

Source: Sunflower Children Author: Sunflower Children Editor: Wuxiu Date: December 1, 2023

The "Ask Anything About Medulloblastoma" column invites experts in the field of pediatric brain tumors to answer specific questions regarding various aspects of medulloblastoma. Today, we present the 16th edition and encourage everyone to leave their questions in the comments section!

1. Can recurrent medulloblastoma be treated with radiotherapy again?  

Recurrent medulloblastoma often leads to a difficult prognosis with long-term survival being challenging. Salvage treatments may include a second surgery, high-dose chemotherapy, targeted therapies, and, of course, re-irradiation. Re-irradiation can be performed using either local radiation or whole central nervous system radiation, with the choice depending on the patient's condition and determined by the physician. Research shows that re-irradiation may improve survival rates for patients with recurrent medulloblastoma, enhancing progression-free survival (PFS) and overall survival (OS). Most patients can complete the planned radiation dose without experiencing severe neurological necrosis or bleeding, indicating that re-irradiation is relatively safe. However, whole central nervous system re-irradiation can significantly impair long-term cognitive function. Therefore, treatment should be personalized, considering the patient's condition, the time interval since the first treatment, and the expected outcomes.

2. What are the side effects of radiotherapy?  

Radiotherapy plays a crucial role in treating medulloblastoma and can be decisive for prognosis. While its benefits are significant, it inevitably comes with adverse reactions, which can be broadly categorized into acute and long-term side effects.

Acute side effects include impacts on the hematopoietic system, leading to decreased white blood cells, reduced immunity, and even anemia; gastrointestinal issues such as loss of appetite, nausea, vomiting, and liver function decline; some patients may experience decreased kidney function; and neurological responses such as limb numbness or localized brain edema, which may lead to secondary localized brain swelling.

Long-term side effects could affect the patient's neurocognitive functions, growth and development, and even potentially lead to secondary malignancies. Although these adverse effects exist, when weighing the pros and cons, the benefits of radiotherapy for medulloblastoma patients outweigh the negative reactions.

Currently, for patients with medulloblastoma, radiotherapy is still recommended. Research is focusing on how to delay the use of radiotherapy as much as possible or how to reduce the radiation dose while maintaining overall treatment efficacy.

3. Can radiation protectants be used on the head before radiotherapy?  

During head radiotherapy, the scalp within the radiation field may experience hair loss, redness, swelling, mild itching, and even pigmentation changes. Skin protectants can be applied before radiotherapy to alleviate and reduce damage. Additionally, sun protection is important; patients should use umbrellas or hats when going outside, avoid scratching the skin, use mild shampoos or lukewarm water to wash the scalp, and refrain from using irritating products like hair clips or blow dryers.

4. What should be done if bone marrow suppression occurs during radiotherapy?  

Whole-brain and whole-spinal irradiation significantly affect the patient's blood counts, easily leading to bone marrow suppression, which requires prompt treatment to avoid interrupting radiotherapy and affecting treatment outcomes. Therefore, the blood counts should be monitored 1-2 times a week during treatment. If abnormalities are detected, timely interventions such as white blood cell and platelet boosting treatments should be administered. If white blood cell counts drop, it's important to keep the patient warm, prevent infections, and avoid exposing them to environments that could lead to infections. Granulocyte-stimulating factors should be administered while ensuring there is a 6-8 hour gap between the injection and radiotherapy. If platelet counts decrease, precautions should be taken to prevent bleeding, with careful observation for any bleeding symptoms. Medications such as recombinant human thrombopoietin, recombinant interleukin-11, or eltrombopag may be used. In cases of grade III to IV thrombocytopenia with a high risk of bleeding, platelet transfusions may be necessary. If anemia occurs, nutritional support should be enhanced, encouraging high-protein, high-vitamin, iron-rich, and easily digestible diets; tonics for boosting energy and blood may be used, and blood transfusions might be required if necessary.

5. Will radiotherapy affect children's intelligence?  

For patients with medulloblastoma, whole-brain and whole-spinal radiotherapy is necessary. Whole-brain radiation significantly impacts the developing brain, inhibiting neuronal growth, which can lead to adverse reactions including progressive cognitive impairment, reducing attention, memory, intelligence development, and learning abilities. Generally speaking, daily life is not affected. Studies show that the impact on cognitive abilities is more influenced by age than by radiation dose; for children under 5 years old, whole-brain radiation has a more pronounced effect on cognitive function. Thus, for children under 3 years of age, whole central nervous system radiotherapy is generally not performed.

6. Will radiotherapy affect children's height?  

For patients with medulloblastoma, post-surgery whole-brain and whole-spinal radiotherapy is required. The side effects of radiotherapy are related to the area and volume of exposure. Since whole-brain and whole-spinal irradiation covers a large area, it can significantly impact a child's height development. It is currently believed that if the radiation dose is below 10 Gy, height may be reduced by 2-3 centimeters compared to the standard height for the same age.

However, as the child grows older, the impact of radiotherapy on height gradually diminishes. For children under 12 months, if they receive a radiation dose above 10 Gy, they could potentially lose 7-8 centimeters in height before reaching adulthood. For patients over 10 years old, with radiation doses above 15 Gy, height loss is approximately 4-7 centimeters.

Proofreading | 张铮  

Formatting | Ying Tao  

Proofreading | Zhang Zheng