Yes, radiation can cause cancer years later. It is what is known as a "late effect" for radiation which means a side effect that can show up days, weeks, months, or years after you have radiation, but the odds are pretty low of getting a new cancer later on from the radiation. The important thing to remember with many of the treatments we receive as cancer patients is the benefit of the treatments (radiation, chemo, drugs, etc.), to kill existing cancer cells and prevent future growth of new cancers, outweighs the risk of the long term side effects. Basically your odds of surviving cancer and not having your cancer return are better with the various treatments than they are without treatment. I know I'm more concerned with killing any active cancer cells I have now and preventing them from coming back than I'm concerned about getting a new side effect 20 years from now. If I don't kill the cancer that's here now then I won't be around 20 years from now and that small risk of a side effect 20 years in the future doesn't matter if I'm already dead.

I think that also one should not focus on this as a possibility and one should remain positive in going forward.

Yes it can but I truely believe it's worth raking the chance.