nanuk Member Posts: 1,358 Member
edited March 2014 in Colorectal Cancer #1
I'm reading posts by folks who are in the middle of their chemo protocol, and getting both CT and
PET scans..I'm not sure what the difference is, but my Onc reluctantly OK'd a CT scan after four
treatments, and says that PET results would be skewed by the chemo..(?) Can anyone address this seeming contradiction? Bud


  • shmurciakova
    shmurciakova Member Posts: 906 Member
    Hi Bud. I had CT scans during chemo on two different occasions when my CEA fluctuated just to "be on the safe side" so to speak. My guess concerning the PET scan is that glucose can be taken up by any area of inflammation in the body, not only by cancer. As you know from our prior conversations, I had two small "non-specific" lung spots and was then given a PET scan to see if they could determine whether or not I was having a recurrence. My PET came back NED, however, the larger of the spots showed some uptake - although not what you would expect from cancer. In addition, my PET showed uptake at the area of the incision from my liver resection, in my throat, in my urinary tract, etc.etc.....My guess is that your doc. believes that the chemo would cause areas of uptake because of inflammations due to the chemo that are actually not cancer.? Just a guess based on my limited experience........I'm sure if you ask him what his reason is he would tell you...
    Hope your feeling good! Susan
  • Hey Bud:

    As you know, Bert has had two CATs and two PETs and a colonoscopy today while still on his chemo regime. Like Susan, his doc ordered them because of his CEA being continuously between 5.9 and 8.2....not considered normal range for a non-smoking guy. Anyway, his CAT came back twice showing no evidence of disease however, suspecious looking nodules in the lungs...hence the Pet to determine if these nodules were infact calcifactions or something else or recurrent colon cancer. I too have heard that it has to do with cancer cells and sugar uptake...hence the glow on the Pet. I also know that when Bert get's his scans, they must be done at minimum 10 days after his last chemo treatment so that that scans aren't compromised in any way.

    Hope this helps a little. Take care and stay warm.

    Monika & Bert who are nice and toasty in southern california):o)
  • Kanort
    Kanort Member Posts: 1,272 Member
    Hi Bud,

    I'm not sure why the contradictions, but my oncologist ordered my PET and CT scans because I had a chest XRay and the radiologist read that my one of my calcifications in my lower lung had increased in size. Of course, this caused a considerable amount of anxiety until both results proved negative. The CT scan is a much more reliable test than the chest Xray. I'm not sure why the radiologist thought that there was an increase in size of one of the nodules. Maybe I moved or something...who knows. I have been assured by three doctors that these calcifications were a result of an infection when I was young. Wishing you well and great test results!