Hi marie-lyne, I am a bit surprised to learn that follow-up scans are not arranged after treatment as I think it very essential to find out how effective the cancer has responded to the treatment. Other than Pet/Pet-CT scans, there are also ultra-sound, MRI, CT and Chest X-ray which can do the job equally well. I didn't have PET scan all along and just had a PET/CT scan 3 years post treatment when the tumor marker showed some abnormal signs. Apart from it, I had other scans annually and my situation is very closely monitored. If I were you, I wouldn't take any risk. I couldn't afford to miss anything in my body again.
Good luck,

Karen