On a very general level if one asks the question what causes CML there are no definitive answers except there seem to be three headings of types of influences-1.exposure to radiation,2 exposure to benzene,3 viral changes and infections (abl I believe refers to the Abelson virus and add into this the notion that some cancers may be triggered by an infection and/or genetic changes).
So if you have to undertake radiotherapy in any form say for breast cancer or prostate cancer most physicians will indicate that there may be an enhanced risk of developing leukaemia.Some will warn against too many CT scans because of the radiation.I had lots of CT scans on my lungs in the 1980 s with pretty ancient equipment and in the 90s onwards did too much travelling by flying and exposed myself to high level solar radiation-when I queried this with an oncologist the answer was that there were no studies to show that airline staff developed more cancers in later life except perhaps men were more prone to develop prostate cancer.
Shipyard workers and nuclear power station workers have always been at risk from radiation leaks and accidents and they have a higher likelihood of leukaemias as a result.
I think that if you need radiation therapy to cure or slow down breast or prostate cancers then you have little choice but to go ahead with it whatever the possible consequences for the future in terms of being more likely to develop other cancers.
The other issue of course is if you already have CML are you more likely to develop other cancers -there are no definitive studies I believe, but 4 years ago whilst being monitored by a urologist I was told we need to be more suspicious as male CML patients might be at greater risk of developing prostate cancer.
Add to this as a CML patient if one develops breast cancer or prostate cancer and is then subsequently treated by radiation therapy is your CML likely to re occur more aggressively-answer from my haematologist was that we dont know.
In your situation I dont know how genetics helps unless there are proven studies that indicate that some of us are more prone to developing cancers than others. Historically there has been a lot of research in the area and if one looks at the early chapters in Jessica Wapners book "the Philadelphia Chromosome" then there as a geneticist she attempts to explain to general audiences how certain genes turn healthy cells cancerous and produce the oncogene.
My science background is limited but I am still curious to establish how we might have developed CML and also as a patient what existing risks do we face as we are being treated for our condition.