Pulmonary carcinoid tumours

Abstract

<h3>Key points</h3> Pulmonary carcinoid tumours account for 2% of all lung tumours, with an increase in incidence due to more accurate diagnostic techniques. Carcinoid tumours are relatively slow growing, although prognosis depends on histological subtype; atypical carcinoids have worse prognosis Local pulmonary symptoms occur frequently Paraneoplastic syndromes are dependent on the release of hormones or vasoactive peptides into the systemic circulation. Carcinoid syndrome manifests with diarrhoea and flushing, which can lead to dehydration, hypotension and arrhythmias. Carcinoid heart disease is a severe late complication of carcinoid syndrome, manifesting as valvular right-side heart disease, and is a frequent cause of death. Urinary 5-HIAA and CgA are good biochemical markers of carcinoid tumours. Nuclear scintigraphy techniques with ¹¹¹Indium-pentetreotide and ¹³¹I-MIBG are very sensitive in the diagnosis of metastatic carcinoid tumour and are predictive of response to octreotide therapy. Somatostatin analogues are first-line treatment for carcinoid metastatic tumours. Systemic chemotherapy has limited success and is more effective in aggressive variants of carcinoid tumour; IFN-α therapy can also be used with good biochemical and symptomatic responses, but small effects on tumour reduction. <h3>Educational aims</h3> To describe the epidemiology and prognosis of pulmonary carcinoid tumours. To discuss the pathophysiology and clinical presentation of pulmonary carcinoid tumours. To outline the diagnostic procedures and treatment strategies in carcinoid metastatic disease. To highlight the importance of carcinoid-related heart disease and carcinoid syndrome in the prognosis of carcinoid tumours. <h3>Summary</h3> Carcinoid tumours are neuroendocrine tumours derived from enterochromaffin cells, which are widely distributed in the body. Pulmonary carcinoids account for 25% of all carcinoid tumours and they comprise 1–2% of all lung tumours. The incidence of carcinoid tumours seems to be sharply increasing. Carcinoid tumours can be classified as typical or atypical, ranging from low-grade malignant to high-grade malignant, according to histological characteristics and differentiation level. Carcinoids can be placed in a spectrum of neuroendocrine tumours, ranging from low-grade malignant typical carcinoid to intermediate atypical carcinoid, to highgrade large cell neuroendocrine carcinoma and small cell lung carcinoma. Carcinoid pulmonary tumours can present with lymph node or distant metastases, most frequently at the liver. Carcinoid tumours have the ability to secrete many vasoactive peptides, most frequently serotonin. The hormonal secretion is related to systemic manifestations of carcinoid syndrome and carcinoid heart disease. Combining new diagnostic and treatment modalities in metastatic carcinoid patients may result in better prognosis. The review aims to elucidate the reader on the many aspects of carcinoid pulmonary tumours.