Metastatic spread is the hallmark of malignant disease and occurs by lymphatic spread to regional lymph nodes and by haematogenous spread to distant sites. Metastatic disease is the major cause of death in patients with cancer and the principal cause of morbidity. For the majority of patients, the aim of treatment is palliative, but treatment of a solitary metastasis can occasionally be curative.
Brain metastases
Brain metastases occur in 10–30% of adults and 6–10% of children with cancer and are an important cause of morbidity. Tumours that typically metastasise to the brain include lung, breast, melanoma and colon. Most involve the brain parenchyma but can affect the cranial nerves, the blood vessels and other intracranial structures. The median survival without treatment is 1 month. Steroids can increase survival to 2–3 months and whole brain radiotherapy to 3–6 months. Patients with brain metastases as the only manifestation of an undetected primary tumour have a median survival of 13.4 months. Tumour type influences prognosis; breast cancer has a better prognosis and colorectal cancer tends to be worse.
The diagnosis can be confirmed by CT imaging or contrast-enhanced MRI. Carcinomatous meningitis can be confirmed by finding malignant cells in the CSF and treated with intrathecal chemotherapy. Treatment of brain metastasis includes high-dose steroids for tumour-associated oedema, anticonvulsants for seizures, whole brain radiotherapy and chemotherapy. Surgery may be considered for single sites of disease and can be curative; stereotactic radiotherapy may be considered for patients with solitary site involvement where surgery is not possible.
Lung metastases
These are common in lung, breast, colon, thyroid, sarcoma, renal, germ cell tumours and in tumours of the head and neck. Solitary lesions require investigation, as single metastases can be difficult to distinguish from primary lung tumours, although patients with two or more pulmonary nodules can be considered to have metastases.
Lung metastases are usually identified on imaging studies and the approach to treatment depends on the extent of disease in the lung and elsewhere. For solitary lesions, surgery should be considered with a generous wedge resection. Radiotherapy, chemotherapy, or endocrine therapy can be used as systemic therapy, and treatment options are dependent on the underlying primary cancer diagnosis.
Liver metastases
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