"Sam has no palpable tumors yet, but does have elevated lymphocytes."
Gotcha. Don't care for the elevated lymphocytes but they certainly were caught early. That's in Sam's favor and in yours. Completely understand your concerns about possible treatments though I remain hopeful they'll be less harrowing than you might imagine.
We've owned Siamese for over 35 years. Sam sounds a great deal like our beloved blue point, Edgar III. He was the most laid back, relaxed 'Meezer imaginable. Didn't have to use a carrier to drive him to or from the vet. Nor did we need one in the waiting room as Dobie's and Great Dane's would prance by him. "Ed" was so mellow he made people laugh. I'm sure you're getting the picture.
I mention this because those same qualities translated into making him an outstanding feline patient. He lived with renal failure the last year+ of his life, and may I say he did it well. He'd occasionally have to stay overnight at the vet for a "pump up" of IV fluids. Which, I was told, he took in stride. Minute he was released he'd shake it off, come home, and demand a big dinner. Does that sound like Sam?
As an example, Sam went deaf a couple of years ago. Most kitties, when that happens, get really jumpy, and are generally not good to have around children. Sam? Could not care less. If you startle him, he falls over ( he does this little head roll thing, when you pet him on the back, he will go down head first, and fall completely into a puddle of kitty), and starts purring.
My mom and dad have a lavender point now. She is a superb kitty, too. Never shuts up, though!