I was diagnosed with Melanoma as a 9 year old, and a surgery saved me after some radiation treatments. My mother had cancer 8 times, including lung cancer twice. Feeling doomed is natural for a time. Like grieving, there is a process to dealing with the diagnosis, and it is a little different for everyone. My advice to you would be to call someone at the James, or Zangmeister and have this exact conversation with them...they have folks on staff who do exactly this for patients.
In case anyone was wondering, it's been 24 years since my diagnosis, and I'm still alive. My mom lived to be 61, after beating the shit out of a "Mike Tyson's Punch Out"'s worth of different cancers.