I agree that the what-ifs are the worst when you haven't started treatment yet. once the treatment starts you have enough to do to stay on top of your day to day self-care that it's much easier to stay in the moment.

Before I started treatment, when I got the "what-fs" I tried to focus on things I cold do to help with my care later. I asked friends nearby what sort of support they could give as I was going through treatment (often they volunteered things like willing to get groceries or come over and sit with me for a while so my husband could get a break, but if not I gave them a list of help I might need at some point). Then I made a call list for my husband of the 14 or so helping friends/families that had volunteered something such as taking me to treatments, groceries, giving advice if he wasn't sure about whether to call the doc about something, etc., and listed specifically what they had said they could help with next to their names and their phone numbers.

I made a notebook with a place for all the care instructions about post-surgery, chemo, etc. and a log for medications that I could print out (I think we have an example of somehting like this on this site). I tried to get ahead of things I usually took care of like getting the car tuned up and taking the dog for her shots, etc. so they wouldn't come up in the middle of treatment. Not to mention tried to get the house as clean as possible because I knew my husband wasn't very good at keeping up with that in normal circumstances let alone when he would be taking me to treatments every day.

I started a "Caring Bridges" webpage to keep people updated and an email list. In short, I kept myself busy with being proactive about things that would help me get through treatment and that kept some of the bigger fear away. I also kept a jounral and wrote about what scared me, and talked to supportive people about my fears.

I'm a bit hesitant to share this last one because it sounds like it's about religion but in some ways it is just about the psychology of mindfulness. I also have and had a meditation practice where I just sat with my fear if it came and let it be. That last sounds impossible perhaps and it sometimes felt impossible right after the cancer diagnosis (in my case diagnoses), if I hadn't had the practice for several years before then, I don't think I would have been able to do it at all but it did help me. In my case, I do combine that meditation with prayer, but (research actually shows) it works just as well without the religious side.

Nelie