Expert Q&A: How to Determine Chemotherapy Sensitivity and Effectiveness? Does Changing the Treatment Plan Midway Affect Prognosis?

Expert Q&A: How to Determine Chemotherapy Sensitivity and Effectiveness? Does Changing the Treatment Plan Midway Affect Prognosis?

Source: Sunflower Children's Hospital  

Author: Sunflower Children  

Editor: Gao ZX  

Date: March 25, 2023

To help parents of children with cancer address various doubts during and after treatment, the "Expert Q&A" column is back with a bang! Starting today, senior doctors will answer your questions every week.

This week, we have invited Dr. Guo Haixia from the Pediatric Solid Tumor Group at Southern Medical University Southern Hospital to be our main responder, helping us address questions related to solid tumors.

Dr. Guo specializes in the diagnosis and treatment of solid tumors in children, such as brain tumors, neuroblastoma, lymphoma, hepatoblastoma, Wilms tumor, and osteosarcoma, as well as histiocytic diseases like hemophagocytic syndrome and Langerhans cell histiocytosis. She also works with the Hematopoietic Stem Cell Transplant Center at Southern Hospital to conduct autologous or allogeneic stem cell transplants for various recurrent and refractory pediatric tumors.

01

Q: What role does genetic testing play in the treatment of pediatric rhabdomyosarcoma? Under what circumstances is genetic testing necessary? There are various subtypes of rhabdomyosarcoma, and the treatment outcomes can differ. If chemotherapy is not sensitive, is it meaningful to guide medication based on genetic testing results?

A: Current research on pediatric rhabdomyosarcoma has found that certain common gene mutations and a high tumor mutation burden are associated with local tumor control, disease-free survival, and overall survival. Therefore, genetic testing may be significant for determining subtype, predicting prognosis, and adjusting treatment plans. Additionally, for pathogenic gene abnormalities, if there are recommended targeted therapies, it may be a good option for combination or standalone treatment for children with refractory recurrent rhabdomyosarcoma.

If conditions allow, it is advisable to perform genetic testing on newly diagnosed rhabdomyosarcoma patients to aid in diagnosis and treatment guidance. The gene expression of recurrent rhabdomyosarcoma may change; therefore, it is necessary to perform re-biopsy and genetic testing for recurrent patients as well. If resources are limited, genetic testing can also be considered in cases where clinical manifestations are inconsistent, or tumor pathology is atypical, and in cases of refractory recurrence.

Genetic testing may detect potentially beneficial gene mutations, providing opportunities for precise treatment and personalized therapy. Currently, the types of targeted drugs available are limited, and there is less experience in children, but some can achieve therapeutic effects in patients with poor chemotherapy sensitivity. On the other hand, if resistant mutations are detected, ineffective treatments can be avoided.

02

Q: During treatment, it is often encountered that drug sensitivity tests do not match the actual treatment effects. Is it necessary to conduct drug sensitivity testing?

A: There are many influencing factors when drug sensitivity tests do not align with actual treatment outcomes, such as in vitro vs. in vivo differences, changes in the child’s organ function affecting drug metabolism, and the accuracy of tests. Selective drug sensitivity testing can be performed, with close monitoring of clinical presentations and timely adjustments as needed.

03

Q: For high-risk stage IV hepatoblastoma patients who have undergone liver transplantation, what additional examinations are needed apart from ultrasound during follow-up?

A: Important vital signs, organ functions such as heart, liver, and kidney functions, electrolyte levels, coagulation function, routine blood, urine, and stool tests, and alpha-fetoprotein level should be checked. Cytomegalovirus testing may be done if necessary.

04

Q: In treatment, it is common to encounter cases where tumors do not shrink after chemotherapy. Some hospitals will change the chemotherapy regimen, while others insist on sticking to the original plan. How is chemotherapy sensitivity and effectiveness judged, and does frequently changing the regimen affect prognosis?

A: This question requires a comprehensive consideration of the tumor characteristics, chemotherapy drug properties and dosages, and assessment methods.

1. Tumor Characteristics: Some tumors have moderate to poor sensitivity to chemotherapy and may take longer to respond. Based on clinical experience, the timing for adjusting the chemotherapy regimen can be determined. If the patient’s general condition improves, and laboratory indicators suggest effectiveness, observation time can be extended. Tumors located in the cranial cavity or large tumors with necrosis may also shrink more slowly after chemotherapy. Additionally, some tumors may exhibit increased edema or apparent enlargement after chemotherapy. In immature teratomas during adjuvant therapy or post-treatment, mature teratoma components may accelerate growth; when imaging results and serum marker results do not match, the possibility of growing teratoma syndrome must be considered.

2. Patient Condition: Some patients may need to reduce the dosage or types of chemotherapy at the beginning due to comorbidities or unstable vital signs, first reducing the tumor before formal chemotherapy starts.

3. Assessment Methods: The choice of whether to use more precise MR imaging, PET-CT, or biopsy should be determined based on practical conditions.

If you have many questions as well, you can obtain answers through the following two pathways:

1. [WeChat] — Search for the “Sunflower Children” mini-program, and once you enter, you can use the search keywords feature to get comprehensive information.

2. If you do not find the answers you are looking for in the mini-program, you can click the image below to ask the experts. We will try to have doctors respond within a week and publish the answers.

Column Chief: Zhong Ruitao  

Editor: Zuo Jia  

Layout: Xia Yu  

Proofreader: He Fei