Linfoma More Condition_symptoms Is It Dangerous For A Person With Cancer To Travel By Airplane When They've Been On Treatment?

Is it dangerous for a person with cancer to travel by airplane when they've been on treatment? - linfoma more condition_symptoms

My father has non-Hodgkin's lymphoma and is currently in the pelvis (right), and previously was admitted for 4 to 5 months because of the negative side effects of chemotherapy in the hospital. His veins were so swollen that ended with ulcers. Appeared to have been burned with hot water. He had to undergo skin grafts on both legs.
Now you can influence hardly walk because her leg is swollen and I do not know if the height / altitude, it can be.