Not experienced this with my loved one who thankfully is alive and kicking however I do know of someome who did lose a husband this year who had tumours in the chest area and he did die of respiratory failure.
I also know of someone who lost a husband who had tumours in his lungs but then a tumour appeare din his brain, he did not die of respiratory failure he had a major seizure and did not recover.
My husbands tumours are in his bronchial area - its sucha worry!
Lin