Chapter 24: Oncology

Epidemiology · Leukemia · Brain tumors · Neuroblastoma · Wilms tumor · Lymphoma · Bone tumors · Retinoblastoma · Germ cell tumors · Chemotherapy · Supportive care · Late effects · Palliative care

🧬 Key concepts: Most common childhood cancers (ALL, brain tumors, neuroblastoma, Wilms). Staging, risk-adapted therapy. Fever in neutropenia emergency. Long-term follow-up for cardiotoxicity, secondary malignancies, endocrine late effects.

📖 Pediatric oncology: tumors, treatment & survivorship

🧬 Epidemiology & common tumors
Incidence ~160 per million children. Most common: ALL (30%), brain tumors (20%), neuroblastoma (7%), Wilms tumor (6%), NHL (6%), Hodgkin (4%), osteosarcoma, Ewing sarcoma, retinoblastoma, hepatoblastoma.
🩺 Tumor-specific presentations
Neuroblastoma: abdominal mass, proptosis, opsoclonus-myoclonus. Wilms: asymptomatic abdominal mass. Retinoblastoma: leukocoria, strabismus. Brain tumor: morning headache, vomiting, ataxia, focal signs.
💊 Treatment principles
Risk-adapted therapy: chemotherapy (induction, consolidation, maintenance), surgery, radiotherapy (cranial/spinal), HSCT. Targeted therapy (GD2 for neuroblastoma).
⚠️ Supportive & emergency care
Febrile neutropenia → IV antibiotics. Tumor lysis syndrome (hydration, allopurinol/rasburicase). Superior vena cava obstruction (mediastinal mass → avoid anesthesia/ steroids).
🩺 Late effects & survivorship
Cardiotoxicity (anthracyclines), secondary malignancies (etoposide, alkylators), endocrinopathy (cranial irradiation), neurocognitive deficits, infertility, psychosocial support.

⚠️ Red flags for childhood cancer: Unexplained persistent fever, bone pain, night sweats, weight loss, lymphadenopathy, proptosis, leukocoria, abdominal mass, persistent headache with vomiting, neurologic deficit.

🩺 Diagnostic approach to suspected childhood cancer

History & physical – Duration, systemic symptoms (fever, weight loss, night sweats). Specific signs: abdominal mass (Wilms, neuroblastoma), proptosis (neuroblastoma), bone pain (leukemia, bone tumors), neurologic deficits (brain tumor).

Initial investigations – CBC, LDH, uric acid, electrolytes, renal/liver function. Urine catecholamines (HVA/VMA) for neuroblastoma. Imaging: ultrasound (abdominal), CT/MRI (staging).

Tissue diagnosis – Bone marrow aspirate (leukemia, neuroblastoma). Biopsy (tumor). Immunohistochemistry, cytogenetics, molecular markers (MYCN, 1p36, 11q23).

Staging – CSF cytology (CNS disease). Bone marrow, MIBG (neuroblastoma). CT chest/abdomen/pelvis. Staging systems: INRG for neuroblastoma; NWTS for Wilms.

📌 Clinical pearl: Opsoclonus-myoclonus-ataxia syndrome is a paraneoplastic presentation of neuroblastoma (often low-stage, favorable prognosis).

📋 Stepwise management & supportive care in pediatric oncology

Febrile neutropenia (ANC <500) – Blood cultures, IV broad-spectrum antibiotics (cefepime/piperacillin-tazobactam). Hospital admission. Antifungal if prolonged.

Tumor lysis syndrome prevention – Hydration, allopurinol (or rasburicase if high risk). Monitor uric acid, potassium, phosphorus, creatinine.

Superior vena cava obstruction (mediastinal mass) – Avoid general anesthesia (risk of respiratory collapse). Steroids and emergency radiotherapy/chemotherapy.

Chemotherapy protocols (risk-adapted) – ALL: induction, consolidation, maintenance. Neuroblastoma: high-risk requires stem cell transplant + anti-GD2. Wilms: surgery + chemotherapy (vincristine, actinomycin-D) ± radiotherapy.

Late effects surveillance – Echocardiogram (anthracycline cardiomyopathy). Endocrine: growth hormone deficiency, hypothyroidism, infertility. Neurocognitive: educational support. Secondary malignancy screening.

Palliative care – Pain management, psychosocial support, end-of-life planning. Multidisciplinary team (child life, social work, chaplaincy).

🚨 Oncologic emergencies: Spinal cord compression (steroids + radiotherapy/surgery), hyperleukocytosis (leukapheresis), raised ICP (brain tumor → steroids, urgent neurosurgery), hypercalcemia (hydration, bisphosphonates).

🧠 Reflex prompts: pediatric oncology

🧬 3-year-old with abdominal mass, hypertension, and opsoclonus. Most likely tumor?
Neuroblastoma (stage may be low). Urine HVA/VMA, MIBG, biopsy.
🩸 5-year-old with firm, non-tender abdominal mass, no hematuria. Likely?
Wilms tumor. CT confirms renal origin. Avoid biopsy of Wilms; proceed to nephrectomy.
👁️ Child with white pupillary reflex (leukocoria) on photo. Most likely diagnosis?
Retinoblastoma. Urgent ophthalmology exam, orbital ultrasound, MRI.
🦴 Adolescent with knee pain, night pain, and soft tissue mass on femur. X-ray shows sunburst appearance. Diagnosis?
Osteosarcoma. Biopsy, staging (lung metastases common). Neoadjuvant chemotherapy + surgery.
🌙 12-year-old with cervical lymphadenopathy, night sweats, fever, weight loss. Biopsy shows Reed-Sternberg cells. Diagnosis?
Hodgkin lymphoma (nodular sclerosis common). PET/CT staging. Chemotherapy ± radiotherapy.
🧬 Genetic syndrome associated with Wilms tumor?
WAGR (Wilms, aniridia, GU anomalies, retardation), Beckwith-Wiedemann (hemihypertrophy, macroglossia), Denys-Drash (nephropathy, intersex).
🩸 Fever in a child with chemotherapy-induced neutropenia (ANC 100). Immediate step?
Blood cultures + IV broad-spectrum antibiotics (cefepime or piperacillin-tazobactam).
💊 Which drug is used for tumor lysis syndrome prophylaxis in high-risk leukemia?
Rasburicase (recombinant urate oxidase) or allopurinol + aggressive hydration.
🧪 What is the most common long-term cardiac complication after anthracyclines?
Dilated cardiomyopathy (dose-dependent). Lifelong echocardiographic surveillance.
🩺 What is the first-line treatment for newly diagnosed high-risk neuroblastoma?
Chemotherapy (COG/NB2004 protocol) → surgery → high-dose chemotherapy + stem cell rescue → anti-GD2 immunotherapy (dinutuximab).