Same here endometrial cancer in 2009, recurrence 2016. Radiation and brachytherapy. Mine didn't show on the pet scan either although I think they missed it from the next drs notes. Had I not gone to 4 gynecologist oncologists I would probably be dead by now, no one wanted to use a speculum which one of the drs finally did and saw that it had returned in my vaginal cuff. I was told at the time of my surgery that they got all the cancer so no radiation was necessary. All one can do is be proactive but it is tiring. Hope all goes well for you I know how scary this is.