Kitty's sides swell

My Kitty has been diagnosed with leukemia, so we are not surprised that she has medical problems, but lately the sides of her body have been swelling, as if she were gaining weight, but we know it's not from her diet. She hasn't been meowing, so we don't think she's in pain. Does anyone know what is happening? We will take her to the vet soon.

You are doing the right thing to take her to the vet. He will know what to do for her.
Good luck.