Oncological Emergencies

See also:

• Hypercalcaemia
• Syndrome of Inappropriate ADH Secretion (SIADH)
• Acute Spinal Cord Compression
• Cauda Equina Syndrome
• SVC Obstruction

Cancer and its treatment may lead to a range of potentially life-threatening conditions that require urgent action to correct them. They are likely to present to oncologists, general physicians, emergency departments and primary care practitioners. Assessment of the acutely ill cancer patient should proceed as for any acutely ill person.
Important information to obtain is:

• Nature of the tumour
• Staging of tumour
• The response to therapy
• Current prognosis
• The wishes of the patient and their family

This allows an informed choice to be made about the most appropriate treatment plan. Problems may arise due to effects of the tumour or its products, due to oncological treatment, or be a new problem arising independently of the oncological diagnosis. This article covers the commoner causes of acute illness due to cancer.

This is the commonest serious metabolic disorder associated with malignancy, affecting 10–20% of cancer patients. Malignancies most commonly associated include lung, breast, head, neck, kidney, lymphoma and myeloma. Rates in myeloma may be as high as 40%. Its symptoms may mimic the features of terminal malignancy. It is caused by local osteolytic metastatic lesions, secretion of humoral factors that increase bone resorption and impaired renal calcium clearance. Presenting features include:

• Nausea and vomiting
• Anorexia
• Thirst and polydipsia
• Polyuria
• Lethargy
• Constipation
• Confusion
• Weakness

Investigation

Must measure corrected serum calcium, taking into account the albumin level.

Management

• Hypercalcaemia is a poor prognostic indicator in malignant disease and may indicate uncontrolled tumour progression and metastasis.
• Intervention should be considered where there is a chance of successfully treating the underlying malignancy, or to improve symptoms in a palliative situation.
• It is often not appropriate to treat hypercalcaemia in those with terminal disease and a poor short-term outlook.
• Initial therapy should include intensive rehydration for 12–24 hours with 4–6l of normal saline.
• In patients with serum calcium >3.5–4.0 mmol/l or those with neurological symptoms/renal impairment, bisphosphonates may be started straight away.
• In those with lesser hypercalcaemia, the decision to treat with bisphosphonates can be delayed until rehydration and re-assessment of the calcium level.
• IV Pamidronate is the most commonly used agent, with dose tailored to calcium level, but other bisphosphonates are useful;² oral prophylaxis may need to be continued after acute treatment.
• Corticosteroids, gallium nitrate and calcitonin may be used as second-line or adjunctive therapies.
• Some advocate the use of loop diuretics to reduce renal calcium reabsorption, but it can be difficult to mange overall fluid balance.

Tumour cells may secrete ADH, particularly in the case of small-cell lung cancer. The syndrome of inappropriate ADH secretion affects 1–2% of cancer patients. The condition should be considered whenever a patient with malignancy presents with hyponatraemia. It is often asymptomatic but may cause:

• Depression and lethargy
• Irritability and other behavioural changes
• Muscle cramps
• Seizures
• Depressed consciousness leading to coma
• Neurological signs (such as impaired deep tendon reflexes and pseudobulbar palsy)

Investigation

• U&Es show hyponatraemia.
• Low plasma osmolarity and high urinary sodium excretion.
• Other conditions and some drugs (including chemotherapeutic agents) may cause hyponatraemia, so alternative causes need to be considered and excluded.

Management

Successful treatment of the underlying malignancy will improve the condition. Fluid restriction (500–1000 ml daily) and the use of doxycycline (which induces renal resistance to the effects of ADH), are also employed to correct hyponatraemia. It is important not to correct the sodium level too rapidly due to the danger of central pontine myelinolysis; infusions of hypertonic saline are best avoided.

This syndrome is due to the effects of treatment of the malignancy. There is a reaction to the sudden and large release of cellular lysis products caused by tumour destruction. The body may be unable to excrete and neutralise such toxic products. Those particularly at risk have bulky, treatment-sensitive tumours and renal impairment. High pre-treatment urate, lactate and LDH are also risk factors. Onset is usually within 1–5 days of starting therapy and symptoms/biochemical features include:

• Weakness
• Paralytic ileus
• Cardiac arrhythmias
• Acute renal failure
• Hyperuricaemia
• Hyperkalaemia
• Hyperphosphataemia
• Hypocalcaemia

Investigation

Full metabolic and biochemical profile to detect the above abnormalities. Monitoring of serum lactate, urate and LDH may predict the imminent onset of the syndrome.

Management

• Those at risk should have preventative management by receiving intravenous hydration with normal saline 3–6l/24hrs, with sodium bicarbonate.
• Acetazolamide is used to alkalinise the urine and prophylactic allopurinol is given.
• Diuresis with furosemide or mannitol is used with careful monitoring of fluid status.
• Hyperphosphataemia is treated with oral aluminium hydroxide.
• Rasburicase (recombinant urate oxidase) is a novel treatment that appears effective and safe and is currently undergoing full evaluation.³
• Dialysis may be needed in severe cases.

Cranial metastases affect around a quarter of patients who die from cancer.⁴ Lung, breast and melanoma are the tumours that most commonly metastasise to the brain. The clinical picture varies with site of metastases and the rate of rise of intracranial pressure. Small metastases may bleed and cause acute symptoms. Common symptoms and signs include:

• Headache
• Nausea and vomiting
• Behavioural changes
• Seizures
• Focal neurological deficit
• Falling level of consciousness
• Papilloedema
• Unilateral ptosis or third and sixth cranial nerve palsies
• Bradycardia (late sign)

Investigation

CT or MRI scanning should be conducted urgently to delineate the lesion, if the result is likely to affect the patient's management.

Management

• If the patient has lost consciousness and requires ventilation, then high respiratory rate should be used to lower pCO₂ which helps reduce intracranial pressure.
• Mannitol may be given as a diuretic along with dexamethasone to reduce symptoms and the likelihood of cerebral herniation.
• Further management may involve cranial irradiation, surgery ± radiation or 'gamma knife' radiosurgery, depending on the site, type and number of metastases.

This condition must be diagnosed and treated quickly to prevent permanent neurological disability. It may occur because of extradural spread from a vertebral body metastasis, direct metastases or from a vertebral crush fracture. Its symptoms and signs include:

• Localised back pain in nerve root distribution (may be worse on coughing or straining/sneezing).
• Pain that differs from that caused by intervertebral disc protrusion by being worse when lying down.
• Sensory level; check bladder and bowel function, although these late signs are ominous and may indicate permanent damage; signs from examination may predict the optimal site for imaging.

Investigation

X-rays of vertebrae may show metastases. Myelography can be carried out, but MRI is investigation of choice to delineate the lesion.

Management

Dexamethasone with radiotherapy is the most usual form of treatment, usually under neurosurgical advice. Surgical decompression may be necessary or as a means to gain a tissue diagnosis.

• This is due to partial or complete obstruction of the superior vena cava, preventing return of blood to right atrium from the head, neck and upper limbs.
• Compression, thrombosis, tumour invasion or fibrosis may cause the syndrome.
• Lung cancer (~85% of cases), lymphoma and metastatic tumours most commonly cause it.
• It may also arise a consequence of the use of a long-term indwelling venous catheter.
• Neck and facial swelling, particularly around the eyes, dyspnoea and cough or a sensation of fullness in the head are common presenting features.
• It may also cause hoarseness, headaches, nasal fullness and bleeding, haemoptysis, dysphagia, dizziness and syncope.
• Signs to look out for include swelling and suffusion in the upper body, with increased flow through collateral surface veins over the chest wall.

Investigation

Modern treatment emphasises establishing a diagnosis rather than giving empirical radiation therapy as was previously the norm. Only in cases with a very precipitous rise in intracranial pressure, or acute airway obstruction, is empirical therapy currently given. CXR, sputum cytology and CT or MRI scanning ± tissue biopsy are used to establish a histological diagnosis.

Management

• Diuretics, oxygen and dexamethasone may be used to relieve symptoms whilst making the diagnosis.
• Thereafter, therapy is directed at the underlying cause.
• This is normally chemotherapy for lymphoma/small-cell lung cancer, with early response and resolution of SVC obstruction within weeks being the usual outcome.
• Radiotherapy is usually used for non-chemosensitive tumours or patients who do not respond to chemotherapy.
• Stenting of the superior vena cava can be used to treat resistant cases and relieve symptoms.
• Cases associated with indwelling venous catheters should be treated by removing the catheter and giving anti-thrombotic therapy.