Short history: May 2019 I was diagnosed with Stage 4. The biggest tumour was 9 cm on/by my adrenal. (? I think that's the right English word, but I'm too lazy to look it up again right now.) Started Keytruda. By January 2020 the cancer was mostly gone, and suspected colitis was getting bad, so we stopped. PET scan in February showed that all that was left was one slightly enlarged, slightly active lymph node, and 27 mm of the biggest tumour. That last bit showed no metabolic activity, though. So, my doctor had me do another PET scan in April. That showed nothing active anywhere, and the inactive tumour leftover was 25 mm. NED! :-)
Today I had a three-months-after CT scan. That 25 mm is still there. They think it looks soft and unthreatening. However, my doctor wants me to do yet another PET scan in three months. That would be the third this year! Not to mention the expense, I really didn't handle that last one well at all. I started throwing up in the machine. Ick.
My questions: would you do another PET scan so soon? What about waiting till next year?