Professor Jiang Mawei: Is Whole Central Nervous System Radiotherapy Necessary for Medulloblastoma? Is Chemotherapy Still Needed After Radiotherapy?

Professor Jiang Mawei: Is Whole Central Nervous System Radiotherapy Necessary for Medulloblastoma? Is Chemotherapy Still Needed After Radiotherapy?

Source: Sunflower Children Author: Sunflower Children Editor: Wuxiu Date: November 7, 2023

The Medulloblastoma Q&A column invites experts in the field of pediatric brain tumors to provide targeted answers to various questions about medulloblastoma. Today, we bring you the 11th issue, and we welcome everyone to leave your questions in the comments section! 

1. Is it better to have radiotherapy immediately after surgery, or to have a few rounds of chemotherapy first and then radiotherapy?  

The timing of postoperative radiotherapy depends on the age of the child at diagnosis. For children over 3 years old with medulloblastoma, it is recommended to undergo radiotherapy first followed by adjuvant chemotherapy. For high-risk children under 3 years old, radiotherapy can adversely affect growth, intelligence, and cognitive function, so it is advisable to perform chemotherapy first and then consider radiotherapy after the child turns 3. 

2. Is proton therapy suitable for medulloblastoma?  

In terms of treatment efficacy for medulloblastoma, proton therapy is comparable to photon therapy. The advantage of proton therapy lies in its physical properties (Bragg peak), which minimizes impact on normal tissues surrounding the target area, thereby reducing hematological toxicity, endocrine toxicity, and effects on cognitive function.

3. Is whole central nervous system radiotherapy necessary for medulloblastoma?  

Medulloblastoma is prone to invade the pia mater and can metastasize through cerebrospinal fluid dissemination. For children over 3 years old with medulloblastoma, the current standard treatment protocol consists of surgery followed by whole brain and spine radiotherapy, along with adjuvant chemotherapy. However, for children under 3 years old, some centers consider the impact on growth and development and may adopt a treatment model involving localized tumor bed radiotherapy. Patients receiving localized radiotherapy may experience a higher risk of disseminated relapse.

4. What are the differences in radiotherapy for standard-risk and high-risk medulloblastoma?  

Currently, the Chinese Children's Cancer Group (CCCG) classifies medulloblastoma patients into standard-risk and high-risk groups based on the child's age, extent of surgical resection, presence of metastases, and pathological type. The difference in radiotherapy between the two groups lies in the dosage and the extent of the boost in whole brain and spine radiation. The standard-risk group typically receives 23.4Gy for whole brain and spine, with a boost to 54-55.8Gy for the tumor bed; the high-risk group receives 36-40Gy for whole brain and spine, with a boost to 54-55.8Gy for the posterior fossa. As research on molecular typing progresses, simple clinical classification may no longer meet clinical needs, and adjustments to radiotherapy doses for medulloblastoma under molecular typing conditions are being explored.

5. Under what circumstances is radiotherapy not recommended?  

For standard-risk patients diagnosed at under 3 years of age, postoperative care may consist solely of adjuvant chemotherapy.

6. Is chemotherapy still necessary after radiotherapy for medulloblastoma?  

Yes, chemotherapy is also an important treatment modality for medulloblastoma. 

The treatment of pediatric medulloblastoma is a systematic process; in addition to surgery, systematic radiotherapy and chemotherapy are required. The two modalities are complementary and indispensable. Therefore, once a treatment plan is established by the physician, patients who undergo radiotherapy still need to receive chemotherapy. Of course, different treatment guidelines may have slight variations regarding whether to initiate with radiotherapy or chemotherapy.

For children with medulloblastoma, even after surgery and receiving radiotherapy, chemotherapy should still be administered. In recent years, there has been a trend to delay or reduce the use of radiotherapy as long as chemotherapy can control the disease effectively.

Editing: Zhang Xinghui  

Proofreading: Zhang Zheng