Common pediatric cancers — MCQs

Question 1: A 4-year-old boy with Down syndrome presents with fatigue and recurrent infections. CBC shows WBC 150,000/μL with 90% myeloblasts, hemoglobin 6.5 g/dL, platelets 15,000/μL. Flow cytometry confirms acute myeloid leukemia with megakaryoblastic features (AMKL). The parents are concerned about treatment intensity given their child's baseline developmental delays and increased treatment-related toxicity risk in Down syndrome. Evaluate the treatment approach considering the unique biology and competing risks.

• A. Modified chemotherapy protocol with dose reductions of cytarabine but standard anthracyclines, given Down syndrome-associated AML excellent prognosis (Correct Answer)
• B. Bone marrow transplantation as first-line therapy
• C. Palliative care approach given poor baseline function and high treatment toxicity
• D. Reduced-intensity chemotherapy due to Down syndrome and baseline developmental concerns
• E. Standard AML chemotherapy protocol without modification

Explanation: ***Modified chemotherapy protocol with dose reductions of cytarabine but standard anthracyclines, given Down syndrome-associated AML excellent prognosis*** - Children with **Down syndrome-associated AML (DS-AML)**, specifically the **megakaryoblastic (AMKL)** subtype, exhibit hyper-sensitivity to **cytarabine** due to lower levels of the enzyme cytidine deaminase. - While they have an **excellent prognosis** (cure rates >80%), they face a high risk of **treatment-related toxicity**, necessitating dose modifications to improve safety without sacrificing efficacy. *Bone marrow transplantation as first-line therapy* - **Hematopoietic stem cell transplant** is not indicated as first-line therapy because DS-AML responds exceptionally well to **chemotherapy** alone. - Transplant carries a high risk of **morbidity and mortality**, which is unnecessary given the high survival rates with modified chemo regimens. *Palliative care approach given poor baseline function and high treatment toxicity* - Palliative care is inappropriate as the primary strategy because DS-AML is a **highly curable** malignancy in pediatric patients. - Developmental delays and baseline status do not preclude aggressive **curative intent** therapy, as long as protocols are adjusted for toxicity. *Reduced-intensity chemotherapy due to Down syndrome and baseline developmental concerns* - While toxicity is a concern, broad "reduced-intensity" therapy may lead to **under-treatment** and increased risk of **relapse**. - Specific modifications, rather than blanket reductions, are required to maintain the **high cure rate** associated with the **GATA1 mutation** characteristic of this disease. *Standard AML chemotherapy protocol without modification* - Using standard AML protocols in children with Down syndrome leads to **excessive toxicity**, particularly severe **mucositis** and life-threatening infections. - The unique **pharmacogenomics** of Down syndrome patients requires dedicated protocols like the **Children's Oncology Group (COG) AAML0431** to manage treatment risks.