Hot Spots On Pet Scan

I am one year past surgery, followed by radiation and 6 months past chemotherapy after upper right lobe 9.5cm poorly indifferentiated non-small cancer of the lung. Treatments were for precaution because the tumor had adhered to a small section of the lining of my lung. They think they removed all and no lymph nodes showed positive. I had a PET scan 4 weeks ago that showed "hot spots" where the original cancer was and also near my colar bone. My oncologist suggests we wait and reevaluate after 6 weeks. He says the "hot spots" could be caused by radiation or scarring and that if the cancer is back there is not much they can do anyway. Do hot spots show up from radiation or scar tissue? Should I be concerned?

I think they do as long as there is any activity. As I understand it, the PET shows areas of increased uptake not only relating to cancer but other things like radiation. I'm not sure how long after treatment the activity goes away. Google PET Scan and read about the test.