Thanks for these replies. The concerns I have are that both drugs increase the risk of lymphoma and play around with your immune system -- maybe increasing risk of infection, illness? -- but I suppose that having inflammation in your colon for years is also pretty bad for you, so maybe it's all equal.
I don't love the idea of having infusions but I'll get over it. My doctor prefers that to the self-injector (also not a fun idea) so this is the option he wants to go with.
You hit the nail on the head with the bolded text. The risk with the drugs is very low (0.0004% ish) while the chances of colon cancer with prolonged inflammation can be greater than 40%