Oh, and in relation to your original question, there are some supplements that are not advised to take prior to surgery, or during the other treatments, make a list of your regular supplements because you will probably be asked about them.
You may be called in for a preadmission appointment at the hospital, they will ask about supplements there and will tell you what not to take in the lead up to surgery.
Fish Oil was one I remember, something to do with blood clotting.
Ask your specialists or nurses.
The Pharmasist at the hospital where I went for Chemo checked all my medications and supplements for me.
Glucosamine was apparently not good during chemo and I was not allowed to use my migraine reliever drugs as they interacted adversely with the Antinausea drugs.
I also could not use a natural supplement that contained probiotics as I was neutropenic, and my Oncologist was concerned about unknown bacteria.
I would say just be as healthy and as fit as you can without straining your body.
Mastectomy may affect your flexibility of your arm, so if you need to sort issues with your arm out prior to surgery, it would be a good time to do it.
I wish I had seen the chiropractor before surgery as I am in desperate need now, and can't go until my radiation burns heal.