That’s too bad. Our house cat has lymphoma. She was given one-three months without treatment. If she went through treatment, she might live long enough to finish the treatment. We opted to just keep her as comfortable and happy as possible for the time she has left.
My girlfriend and myself just went through this ourselves with her cat of 16 years Knittnmom. When we knew the end was close the vet gave us some meds for his comfort and he died peacefully with us. Cherish the time you have left, they really are members of our family.