Having been there as a patient, the anger phase passed for me shortly after treatment started. The radiation/chemo phase was somehow different than surgery, likely beacause of the down time that follows surgery when you feel really powerless, as you are sitting around with an idle mind, and are still waiting for the "real' treatment to begin. Of course, in the background, the anger is driven by fear.

Once the radiation and chemo began, I felt more in control, even thought that was largely illusory. That made the anger go away. It surfaced from time to time as I got frustrated with a side effect, or perceived nagging over the need to eat, but all in all it got much better. Hang in there!