Hi Mike
As William suggested - have your dental surgeon connect with your oncologist as to what would be best for you.
I had treatment in 2006 - nasopharyngeal carcinoma IV, with 35 sessions of radiation and also with chemo thrown in. A few years ago, my root canal in the front teeth broke and option was either dental implant or dentures. Dentist suggested dental implant, but my oncologist was not in agreement for the dental implant. But, believe my dentist managed to convince my oncologist that since it's in the front - it should be ok. I eventually got the dental implants - but then in my case - the implant occurs to the two front teeth.
Hope this helps!