Hi Johanna,
You sound like a pretty tough cookie.
I had radiation/chemo as shown below, and made it through relatively well - I am pain free from the radiation and chemo other than an occassional minor sore throat on one side (I still have some stiffness and muscle fatigue from the neck dissection, but these are minor relatively speaking). Everyone one is different though, and some take the treatment harder than others - but they make it through!
There's a thread from yesterday where I and others discuss saliva issues after treatment (see "Newbie" below started by kenk - you can also search the forum under "saliva"). There are measures intended to protect the saliva glands during radiation treatment as well as medications intended to stimulate the saliva glands after treatment to help get them functioning again.
To me, the saliva issue is not so serious that it would weigh at all in the consideration to treat or not treat the cancer. Everyone's saliva issues will differ according to the individual, and I for one have been making saliva and I'm only 5 months out of treatment.
But we all know where untreated cancer goes, and to me that doesn't seem like a very good option. You will find a wealth of caring and support on this website from people who have had radiation/chemo or been caregivers to loved ones, helping them through.
Best wishes,
Chris