8.3 Medical Oncology & Oncological Emergencies
Key Takeaways
- Neutropenic sepsis is defined as absolute neutrophil count (ANC) <0.5 x 10^9/L (or <1.0 x 10^9/L with predicted drop to <0.5) with temperature >38.0°C or signs of sepsis; empiric broad-spectrum IV antibiotics (e.g. piperacillin-tazobactam) MUST be administered within 1 hour.
- Tumor Lysis Syndrome (TLS) is characterized by hyperuricemia (>476 µmol/L), hyperkalemia (>6.0 mmol/L), hyperphosphatemia (>1.45 mmol/L), and hypocalcemia (<1.75 mmol/L); rasburicase (recombinant urate oxidase) is first-line treatment for high-risk patients.
- Metastatic Spinal Cord Compression (MSCC) requires immediate high-dose intravenous dexamethasone (16 mg daily) and urgent whole-spine MRI within 24 hours followed by neurosurgical decompression or emergency radiotherapy.
- Hypercalcaemia of Malignancy (serum calcium >3.0 mmol/L adjusted) is treated initially with aggressive IV 0.9% sodium chloride rehydration (3–4 L/24 hours) followed by IV bisphosphonates (zoledronic acid 4 mg over 15 mins or pamidronate 60–90 mg).
- Superior Vena Cava Obstruction (SVCO) presenting with facial oedema, venous distension, and stridor requires oxygen, high-dose dexamethasone, and urgent endovascular stenting or emergency radiotherapy.
8.3 Medical Oncology & Oncological Emergencies
Acute Oncological Emergencies: Resuscitation & Risk Stratification
Oncological emergencies represent life-threatening complications resulting directly from systemic malignancy or cytotoxic cancer therapy. Rapid identification and immediate protocol-driven interventions are crucial to prevent irreversible organ damage or mortality.
1. Neutropenic Sepsis
Neutropenic sepsis is a medical emergency occurring in cancer patients receiving myelosuppressive chemotherapy.
Diagnostic Definition & Clinical Criteria
- Neutropenia: Absolute Neutrophil Count (ANC) <0.5 x 10^9/L, or expected to fall below 0.5 x 10^9/L within 48 hours.
- Fever / Sepsis: Single oral temperature >38.3°C, or persistent temperature >38.0°C for over 1 hour, or any clinical signs/symptoms of systemic sepsis (hypotension, tachycardia, altered mental state) regardless of temperature.
Management & Risk Stratification Protocol
Empiric intravenous antibiotic therapy MUST be initiated within 1 hour of arrival ("door-to-needle time"), prior to receiving blood culture results or imaging.
| Clinical Parameter | Low-Risk Neutropenic Sepsis | High-Risk Neutropenic Sepsis |
|---|---|---|
| MASCC Risk Index Score | ≥21 points | <21 points |
| Clinical Presentation | Outpatient, hemodynamically stable, no organ dysfunction | Inpatient, septic shock, pneumonia, severe mucositis, renal failure |
| Expected Duration of Neutropenia | Short (<7 days) | Prolonged (≥7 days) |
| Empiric Antibiotics | Oral fluoroquinolone (Ciprofloxacin) + Co-amoxiclav (outpatient) | IV Piperacillin-tazobactam (4.5 g 6-hourly) OR Meropenem (1 g 8-hourly) |
| Addition of Vancomycin / Teicoplanin | Not routinely indicated | Indicated for catheter infection, severe mucositis, MRSA colonisation, shock |
MRCPI Exam Pearl: Do not delay antibiotic administration to obtain central line cultures or imaging. If a patient is penicillin-allergic (severe anaphylaxis), administer IV Meropenem or Ciprofloxacin plus Vancomycin.
2. Tumor Lysis Syndrome (TLS)
Tumor Lysis Syndrome occurs due to rapid, massive destruction of malignant cells (commonly in high-grade haematological malignancies like Burkitt lymphoma, ALL, or bulky AML) releasing intracellular contents into the systemic circulation.
Cairo-Bishop Diagnostic Criteria for TLS
Laboratory TLS requires ≥2 of the following biochemical abnormalities within 3 days before or 7 days after initiation of chemotherapy:
| Biochemical Parameter | Laboratory Threshold | Percentage Change | Clinical Manifestations |
|---|---|---|---|
| Hyperuricemia | >476 µmol/L (>8.0 mg/dL) | 25% increase from baseline | Urate nephropathy, acute kidney injury |
| Hyperkalemia | >6.0 mmol/L (>6.0 mEq/L) | 25% increase from baseline | Cardiac dysrhythmias, sudden cardiac death |
| Hyperphosphatemia | >1.45 mmol/L (>4.5 mg/dL) | 25% increase from baseline | Calcium-phosphate crystallization, renal failure |
| Hypocalcemia | <1.75 mmol/L (<7.0 mg/dL) | 25% decrease from baseline | Tetany, seizures, QT prolongation, carpopedal spasm |
Clinical TLS is defined as Laboratory TLS PLUS at least one clinical complication: acute kidney injury (creatinine ≥1.5x upper limit of normal), cardiac arrhythmia, or seizures.
TLS Prophylaxis & Treatment Strategy
- Vigorous Hydration: Intravenous 0.9% sodium chloride at 3 L/m²/24 hours to maintain high urine output (>100 mL/m²/hour).
- Hypouricemic Agents:
- Allopurinol (300 mg daily): Xanthine oxidase inhibitor. Prevents new uric acid formation. Indicated for low/intermediate risk TLS.
- Rasburicase (0.2 mg/kg IV): Recombinant urate oxidase enzyme. Converts existing insoluble uric acid into soluble allantoin for excretion. Indicated for high-risk TLS or established hyperuricemia. (Contraindicated in G6PD deficiency due to risk of severe haemolysis and methemoglobinemia).
3. Metastatic Spinal Cord Compression (MSCC)
MSCC occurs when metastatic tumor tissue compresses the spinal cord or cauda equina, most frequently originating from prostate, breast, or lung carcinoma.
Clinical Presentation & Diagnostic Emergency
- Symptoms: Progressive axial back pain (worse lying flat, nocturnal, coughing), bilateral lower limb weakness, sensory level deficit, and sphincter dysfunction (urinary retention/overflow, faecal incontinence).
- Gold-Standard Investigation: Urgent Whole-Spine MRI performed within 24 hours of clinical presentation (or <12 hours if rapid neurological deterioration).
Emergency Management Algorithm
- High-Dose Corticosteroids: Immediately administer IV Dexamethasone 16 mg (as 16 mg single dose or 8 mg BD) with oral proton pump inhibitor cover to reduce vasogenic cord oedema.
- Patient Positioning: Strict flat bed rest with log-rolling until spinal stability is formally assessed.
- Definitive Treatment:
- Neurosurgical Decompression & Stabilization: Preferred for patients with spinal instability, single-level compression, unknown primary tumor, or previous radiotherapy to the site.
- Radiotherapy: Preferred for radio-sensitive tumors (lymphoma, myeloma, small cell lung cancer) or non-surgical candidates.
4. Hypercalcaemia of Malignancy & SVCO
Hypercalcaemia of Malignancy
Driven by parathyroid hormone-related peptide (PTHrP) secretion (squamous cell carcinomas) or osteolytic bone metastases (breast cancer, multiple myeloma).
- Clinical Features: "Stones, bones, abdominal groans, and psychic moans" (polyuria, polydipsia, confusion, constipation, shortening of QT interval).
- Emergency Management:
- Volume Expansion: IV 0.9% Sodium Chloride 3 to 4 Litres in 24 hours to restore GFR and promote calciuresis.
- Bisphosphonates: IV Zoledronic Acid 4 mg over 15 minutes (or IV Pamidronate 60–90 mg over 2–4 hours) administered after adequate rehydration. Onset of action is 24–48 hours; peak effect at 4–7 days.
- Denosumab: Monoclonal RANKL inhibitor (120 mg subcutaneous) for refractory hypercalcaemia or severe renal impairment.
Superior Vena Cava Obstruction (SVCO)
Obstruction of blood flow through the SVC caused by mediastinal mass (non-small cell lung cancer 50%, small cell lung cancer 25%, lymphoma 15%).
- Clinical Presentation: Facial and neck swelling, dyspnoea, cough, distended neck/chest wall veins, and Pemberton's sign. Stridor indicates critical upper airway compromise.
- Emergency Management: Elevate head of bed, high-dose IV dexamethasone (16 mg daily), oxygen therapy, and urgent percutaneous endovascular stenting (provides rapid relief within 24–48 hours) or emergency radiotherapy/chemotherapy depending on histology.
A 58-year-old male receiving combination chemotherapy for small cell lung cancer presents 10 days post-chemotherapy with a temperature of 38.6°C. Blood pressure is 105/65 mmHg and heart rate is 108 bpm. Absolute neutrophil count is 0.2 x 10^9/L. MASCC risk index score is calculated at 17. What is the single most important immediate action?
A 19-year-old male with newly diagnosed bulky T-cell Acute Lymphoblastic Leukaemia develops acute oliguric kidney injury 24 hours after commencing induction chemotherapy. Serum biochemistry reveals uric acid 610 µmol/L, potassium 6.4 mmol/L, phosphate 2.10 mmol/L, and corrected calcium 1.62 mmol/L. ECG shows peaked T-waves. In addition to cardiac membrane stabilization and measures to lower potassium, which agent is specifically indicated to convert serum uric acid to highly soluble allantoin?
A 62-year-old female with metastatic breast carcinoma presents with a 3-day history of worsening mid-thoracic back pain that increases when lying flat and wakes her at night. On examination, she has bilateral lower limb weakness (grade 4/5 power), hyperreflexia at the knees, and an extensor plantar response on the left. What is the immediate first-line management step while arranging an urgent whole-spine MRI?