2.1.1 Lung cancer is often at an advanced stage when it is diagnosed, with low survival rates. Patients can develop endobronchial lesions that obstruct the major airways, causing symptoms such as dyspnoea, cough, haemoptysis and postobstructive pneumonia. Bronchial obstruction may lead to gradual asphyxiation.
2.1.2 The aim of treatment in patients with malignant endobronchial obstruction is mainly palliative. Current treatment options include a variety of endobronchial therapies such as bronchoscopic resection, brachytherapy, laser ablation, photodynamic therapy and stenting. Externalbeam radiotherapy and chemotherapy may also be used for palliative treatment.
2.2.1 General anaesthesia is usually used. A cryoprobe is inserted through a bronchoscope to reach the tumour; the probe diameter selected depends on the size and position of the tumour. After a period of freezing, the tumour is allowed to thaw until the probe separates from the tissue. The freeze/thaw cycle may be repeated two to three times in the same place. The probe is then moved to an adjacent area and the process is repeated until the whole tumour has been treated. Any resulting necrotic tumour material is then removed with forceps or using the cryoprobe. Further necrotic material may be expectorated during the following 24–48 hours. The procedure can be repeated if necessary.
2.2.2 Cryotherapy does not provide immediate relief of bronchial obstruction and is therefore not suitable for the emergency treatment of acute respiratory distress.
2.3.1 The main aim of the procedure in the studies was palliation of symptoms such as cough, dyspnoea and haemoptysis. In one case series of 521 patients, 86% (448/521) had improvement in one or more symptoms and quality of life scores were significantly improved. Dyspnoea improved in 59% (300/507) of patients. In two further studies, dyspnoea improved in 71% (12/17) and 81% (87/107) of patients. For more details, refer to the Sources of evidence.
2.3.2 The Specialist Advisors did not express any major concerns about the efficacy of this procedure.
2.4.1 A large case series study reported in-hospital mortality of 1% (7/521), which was due to respiratory failure. This study also reported that 3% (16/521) of patients developed respiratory distress after the procedure.
2.4.2 A case series study of 27 patients reported one death due to myocardial ischaemia. Another study of 22 patients reported one cardiopulmonary arrest during the procedure. Two studies reported changes to the heart rhythm in 2% (12/521) and 11% (3/27) of patients. For more details, refer to the Sources of evidence.
2.4.3 The Specialist Advisors listed haemorrhage, fistula formation, cardiac arrhythmias, respiratory distress and infection as potential adverse effects.