People with advanced cancer may notice a swelling on the face or neck.
According to Cancer Research UK, this is called superior vena cava obstruction (SVCO).
As Macmillan UK explained, the superior vena cava (SVC) is a big vein in the middle of the chest.
It carries blood from the upper body to the heart. If cancer presses on the SVC, it may block the flow of blood along this vein.
The charity said: “SVCO is usually caused by a lung cancer near this vein and less commonly other types of cancer.”
