Body Horror
I think that scene in Annihilation where the guys intestines are writhing like snakes captures how I feel a lot of the time
From the comments
James Petrosky: Cancer is living body horror. There are constant new and grotesque violations. You always know the ultimate cause (those immortal detector cells), but your never sure what devious plot they're on now.
You know how the movie ends, and what the last few minutes look like. But you'll never predict that third act bear monster / the loss of the ability to feel comfortable when your sitting or lying down. The violations do not stop.