How can I help my deal with the swelling in her legs, resulting from her cancer?

All i have is personal experience, but my dad had lung cancer twice, The only think that seemed to help, and even the doctors did it before he passed, was just to alway have them up -- staying off his feet at all times unless to go the bathroom! When his arms began to swell we did the same thing. The arms being smaller was more effective! Rubbing his legs and moving the blood back up seem to bring comfort to him and help with the swelling also.

My mother had leg swelling due to cancer she was put on a bloodthinner that has helped.