Thanks for posting the X-ray. It sounds like a good diagnosis. Unfortunately cancer, especially ovarian cancer, is very common in hens. Sorry that you may lose her at some point. I usually keep my sick chickens with their flock, unless they are picked on, since they seem to enjoy being with them.
How long ago did she lay an egg, and does she lay normal eggs regularly? If you feel that she is egg bound, then give her 1/2 calcium tablet or Tums orally into her beak to swallow. Several things could feel like a hard mass, and besides an egg, there could be salpingitis and lash egg material...