Obstruction of either the central airways or superior vena cava is a complication of cancer which can cause severe breathlessness.
What is known
Although there is not high level evidence to support these treatments, treatment guidelines recommend that for central airway obstruction causing dyspnoea, either endobronchial treatments (laser, brachytherapy, electrocautery, cryosurgery, stenting) or external beam radiotherapy may provide effective palliation. [1-2] A systematic review comparing external beam radiotherapy plus brachytherapy for obstruction with external beam radiotherapy alone showed no strong evidence to support adding brachytherapy to external beam radiotherapy, however. External beam radiotherapy alone seemed to be more effective than brachytherapy. 
There is evidence that both endovascular stenting and radiotherapy are effective in malignant superior vena cava obstruction. [1-2]
Steroids are frequently recommended for palliation in superior vena cava obstruction, but this practice has not been studied.
Implications for practice
- Chemotherapy should be considered, where clinically appropriate, as the first line treatment for chemosensitive tumours causing obstruction. 
- Based on a recent systematic review, patients with non-small cell lung cancer who have recurrent obstruction after being treated with external beam radiotherapy, could be considered for treatment with brachytherapy. 
- Referral for stenting or radiotherapy for superior vena cava obstruction, or radiotherapy, stenting or endobronchial treatment for central airway obstruction should be offered if clinically appropriate.
- Dyspnoea associated with obstruction can be severe and distressing. If active interventions are either inappropriate or impossible, palliation should focus on pharmacologically minimising distress for the patient (and for their family and caregivers) by promptly treating with opioids, and / or anxiolytics and sedatives. [5-6]