I can't say how one ought to react, but I can relate my own experience as 2 months shy of 5 years post-diagnosis with stage 3-c grade 2 endometrial adenocarcinoma.
I didn't do a lot of research on the disease because Dr. Google's statistics scared me. I did do a fair amount of research on doctors, and surrounded myself with doctors I like, trust, and believe in, and who seem to like, trust, and believe in me. I talked with doctors a lot. Fired two who wouldn't take responsibility for screwing up. Once I had all the right doctors I did what they told me to do, which included surgery, chemotherapy, radiation - including internal radiation which as I remember is called brachytherapy, and more chemotherapy.
It wasn't a great year, but none of it was all that bad, and I would do it again with the same doctors.
I told only close family members and co-workers. I didn't like to talk about it, and kept conversations short except with doctors.
The worst part of losing my hair was that it's like wearing a sign that says "I have cancer." I didn't want anyone's pity. My hair came back in white at age 58, and when it got about an inch long I had it dyed fuschia as a public declaration of "don't pity me." The fuschia didn't last long, nor did the white hair. It's grey and brown as ever now.
You know it really, really rankles me when people imply that surviving cancer is all about attitude. That's BS, and is also victim blaming. I have known people with magnificent attitudes who have died and people with lousy attitudes who have survived. I lay my survival to my doctors and to blind luck.
In a nutshell, then, I guess my take on how best to react is to surround yourself with doctors you trust, then do as you're told. My heart is with everyone facing the disgnosis. It's certainly draws you up short.