My dog has a huge tumor in her abdomen...?

and I was talking to my mom tonight as we have been discussing the issue of removing it. With it being a heavy cost, and my dog being 10 1/2 she has risks obviously. Well we were thinking she eats a lot of my cat's feces, which is normal for a dog to want to do that, but because we have clumping litter she ends up eating the litter every time she eats the feces. She has had the tumor about 2 1/2 years, and has been eating the litter since we got her at like a year. So that's like 9 1/2 years she has been eating litter. Is there anyway this tumor could result from the litter since it's indigestible?