"Palliative use of non-invasive ventilation in end-of-life patients with solid tumours: a randomised feasibility trial"  
Lancet Mar 2013
http://www.lancet.com/journals/lanonc/article/PIIS1470-2045(13)70009-3/fulltext
"Interpretation

Our findings suggest that NIV is more effective compared with oxygen in reducing dyspnoea and decreasing the doses of morphine needed in patients with end-stage cancer. Further studies are needed to confirm our findings and to assess the effectiveness of NIV on other outcomes such as survival. The use of NIV is, however, restricted to centres with NIV equipment, our findings are not generalisable to all cancer or palliative care units."