Welcome mate. Sorry to hear about your ailment, I am sure once its done and gone you will have the added desire to smash it in the gym.
So your currently undergoing treatment? Chemo I guess. Are you still keeping active, walks and light stuff, reason I ask is father in law has been fighting a long battle with leukemia and they told him to stay as active as possible through chemo ,even though ya don't feel like it, its doing you good, good for the body but more importantly the mind