Depending how long its been open and stored may effect its efficacy. May be worth contacting your vet.As mentioned on your other thread, it can be harsh on gut and kidneys too so have to weigh that up against potential benefit.
Tumours, especially that size can be quite aggressive and while it may be linked to her leg paralysis, is likely progressing to her other organs.
I had a hamster many years ago, called Bear, who developed a tumour where Gracies was. Within a few weeks, two more developed and grew at an alarming rate. He was bright and alert and I did eventually help him along as they were getting so large. I recently found a (poor) video of him and cried at the size I let them get. I'm just sharing this so you know I do understand
Bear twilight years - YouTube