Hello,
You ask a number of questions, which is only to be expected when you get a close relative diagnosed with a serious illness. My wife was diagnosed with cml in 2003, and I certainly went through a period of questioning many aspects of the illness and the treatment options.
I am sure you will find a lot of support from this site, there are contributors who have many and varied experience of cml and who would be very willing to share those experiences with you.
You seem to raise two main points:
1. Prognosis for cml
With the advent of drugs like Glivec, the treatment of cml has been revolutionised. Many people are experiencing very good results, and the prognosis is so much better evene than it was 6 - 7 years ago. These drugs are NOT a cure for cml, but hopefully they keep the condition under control. It is important that you father is cared for by an experienced Haematologist - if he can be seen at one of the specialist centres so much the better (I'm assuming you are in the uk)
Hopefully he has already had a consultation with an appropriate specialist, or will be soon.
2. Cause of cml
The cause of cml is not really known, however exposure to ionising radiation, or to certain chemical solvents have been implicated (especially benzene).
In your father's case he obviously has been exposed to the solvents in paints etc.
However, I don't know if anyone will come up with a definitive answer on this matter.
Hence, I'm not too sure whether anyone would suggest he gives up his work to improve the prognosis. To a certain extent, the damage to the chromosomes will have already occurred - this is what causes the proliferation of white cells in cml. Whether continuing exposure to solvents etc will worsen this, is possibly unknown, unless someone knows anything else about this.
Best wishes to yourself and your father
Paul