reoccurance during radiation

Hi all,

I am on my radiation treatment 26 sessions will fin next week. Want to ask about the like;lyhood of reoccurance during rad? Is it possible regardless of your cancer type? Well I though rad is sooo tough that it will destroy any remaining cells, so how come reoccurance? I am not diagnosed with one, but worried, specially that my path.report says the cancer is found in the dermal lymphatic system!!!

Anyone can help?