I find it helps to think about what ifs and work backwards.
Would you ever give chemotherapy to your cat? For me the answer would be no.
So working back from that, there is no point in me giving my cat a biopsy for a liver lesion, as no way is the cat having chemotherapy.
This way, this decision turns out to be made.
If the vet has a very convincing argument that whatever it is could be cured with one surgery alone, I might be prepared to do that.
So decision would be different.
When my cat was much younger she had a huge mass on her back. I was fairly sure it was benign, but had it removed on the basis that if it wasn't we would be know her life was short and not make her go out in the rain, feed her what she wanted and generally spoil her.
It was benign so back out in the rain she went.
She's got another one now - am leaving it on the basis she's 15 and the stress to her isn't worth it and we now spoil her anyway.
You just have to make your decision based on what is right for the cat at the time. I wish you and your cat all the best.