If the results do come back positive, your vet may refer you to a pet oncologist. Talk to that oncologist (or your vet) about the various available treatments and how cats handle them. Generally speaking, animals handle chemo much better than humans.
While I have not had a cat with cancer, a friend of mine did and opted to treat her, although the cat was about 12 years old. Several rounds of treatment did buy the cat a couple of years, and they were not bad years, although each round of treatments were 4-6 weeks each time.
I had a dog with cancer, so I understand your worry and your concern that you make the right decisions for your pet (my dog's cancer would not have responded to chemo so I opted to not treat him). The best thing you can do is to get as much information as you can, which you are doing by posting to this forum. If you have a university in your state that has a veterinary school, you might want to contact that department to see if they are doing any studies or can provide information to you.
Keep up a positive outlook. I hope everything turns out okay.
"God gave you your body as a gift, so you should take care of it." - My Mom