Hi. I had a similar situation with a roborovski with tumours. Surgery would have involved such a large part of his body it seemed too much. He lived a good six months after the lumps appeared, and they got bigger and affected his mobility but he was quite happy and still using his wheel and enjoying food.
What I did was to make everything a level surface by putting hemp mat over the top of the substrate. He couldn’t walk on the squishy surface of substrate. By putting the hemp mat on the top the level was still right in his cage (hemp mat just in the cage base would have been a bit hard too.). It also allowed to have the surface slightly undulating in places but still flat. I cut holes in the hemp mat to fit his food bowl and sand bath in so they were pushed down in the substrate and the top level with the hemp mat and had hemp mat “steps “ pieces up to his wheel so he could get straight in without needing to climb in.
Yes I would remove the level . You can add more floor hideouts etc to make up for it. An upturned Sputnik or cardboard box hide eg.
Our Robo kept going on Metacam pain reliever for some time. In the end I had to have him pts as he lost so much weight and had started to chew at his lumps. So he was suffering and in pain. The vet saI’d he was trying to amputate them himself.
It is a hard decision. I often thought I should have tried the surgery but it was too late by a certain stage. So you just make the best decision at the time to let them live out their lives one way or the other. I learned from that that Metacam helps but isn’t enough for the pain of cancer later on.
How old is your hamster? What I would say is a hamster can do fine with three legs. Depending on how old now. Many hamsters have amputations - sometimes due to injury. But before deciding that I think you would want to know if the lump is malignant or not and if it is malignant, whether the cancer has spread. I think that would mean a biopsy and a scan. Which is also putting the hamster through quite a few processes.
Another option may be to just have the surgery without knowing and hope for the best. You said “at her age” so I’m guessing she is not young. In which case just keeping her comfortable is probably the best thing.
I have some photos of Nugget’s “disable friendly “ set up. Can’t post them right now as I’m in my phone but if you look at “Nugget’s thread” linked below, they’re in there. He got the lumps age 18 months and lived to the age of two which is a good age for a hamster.
Nugget's thread