PET/CT 5 weeks post rads revealed increased SUV

greentea98 Member Posts: 10 Member
edited June 23 in Colorectal Cancer #1

So my dad went 25 fractions of radiation (45 Gy) for pelvic radiation and sacral met which he finished on 11 May, 2022. Last PET scan was done in Mar 2022 and the recent PET scan was just done yesterday in (June 2022).

ill defined soft tissue lesion in pelvic cavity (SUVmax 8.54 vs 8.16, 46x43 vs 45x41 mm). It was SUVmax 7.78 pre-radiation and size was 2.3x3.1cm. It also says lesion is inseparable from adjacent bowel loops. Significant perlesional fat and stranding nodularity is seen.

Negligible FDG avid few small subcentimetric reptroperitoneal, abdominal and pelvic lymph nodes are seen. No size significant FDG avid lymphadenopathy in abdominal and pelvic region.

And the sacral lesion has also gone from SUVmax 8.8 to 9.99. It says "intense FDG avid predominantly sclerotic osseous lesion in proximal body of sacrum at S1 vertebra.

Though post radiation(1 month after treatment) CEA has dropped to 1.98 which was about 4.8 (pre-treatment).

Our doc pre-treatment told us that the radiation will just eradicate these mets and if somehow they lived they will get too small then the chemo can finish them off. I have no idea what to do now.

What should be my next step?


  • NewHere
    NewHere Member Posts: 1,392 Member
    edited June 23 #2

    I think I read your post correctly.  

    One tumor you described was the SUVMax 8.54 x 8.16 Size 46x43 vs 45 x 41. 

    The second seemed to be half description (SUV max 7.78 pre-radiationand size 2.3 x 3.1 but nothing post)

    The third is the SUVMax 8.8 to 9.99

    Anyway, it seems that some things grew/have more uptake since the May PET.  Let me start with, I am not a doctor or expert.  I have dealing with this 7-1/2 years.   I had Mets to my psoas muscle that went into spine in 2018.  Had three rounds of radiation.  Things stopped growing/being active.  Until this year.  They all started up.  I had fusion of spine and then 5 rounds of radiation to psoas and spine.  At the time of the first radiation the tumors did not shrink for the most part. They just stopped being active if I recall correctly.

    Both times I was given steroids because there can be an uptake in inflammation and activity (to some degree) for awhile following the treatment.  The first time my pain was through the roof (before they gave me steroids) at least two weeks out.  There are also sometimes certain “margins of error” in reads of all these scans.  In other words a couple of points.  Could waiting a bit longer between PET scans show different results? I do not know the time frames. Also is a SUVMax of 8.54 vs 8.16 that much of a difference?  I don’t know if that can just be the read.  There have been studies about how radiologists read things differently. Even the same one twice. The differences I see in my reports is often kind of eye opening

    Again, not an expert, but  my general understanding is that chemo working on tumors when in the spine (not just meaning into the bone, but in the area in general, doesn’t really happen.  I was basically told when the others I have grow large enough to be problems, radiation or surgery. 

    As to CEA, it is a good indicator for me. Not as much for others. If I saw a drop, I would be happy. But again, for many it is not an indicator.

    I would find out a bit more detail about

    1.) Find out what testing has been done on the tumors. What mutations were found, etc. Most places are doing this now. Some more than others. It is very important. I am at MSK and they do a good job. I also was at a trial at Yale and had a report from FoundationOne. They are all valuable. FoundationOne lists trials based on mutations. What drugs are known to work. Or not work. Etc.

    2.). Timing/Reading of PET scan. Could it be the factors I mentioned?

    3.). What is the proposed chemo?

    4.). Plan ahead, which includes looking for trials and keeping on top of that.

    Please check the following two links. The discuss what I mention above. I decided to look around to see if I was recalling things correctly .

    How radiation therapy works against cancer

    At high doses, radiation therapy kills cancer cells or slows their growth by damaging their DNA. Cancer cells whose DNA is damaged beyond repair stop dividing or die. When the damaged cells die, they are broken down and removed by the body.

    Radiation therapy does not kill cancer cells right away. It takes days or weeks of treatment before DNA is damaged enough for cancer cells to die. Then, cancer cells keep dying for weeks or months after radiation therapy ends.

  • greentea98
    greentea98 Member Posts: 10 Member

    Thanks for reply. There are actually 2 places of disease not 3. I tried to write the same language from the PET/CT report so that might have caused some confusion since they gave 2 SUVmax values for pelvic recurrence post-rads.

    The disease is actually a pelvic recurrence adjoining bowel loops i guess (pre-radiation: 2.3 x 3.1cm SUVmax: 7.8, post-radiation: it showed 2 different SUVmax values and different sizes for both) which is slightly increased. And the second is a sacral lesion (at S1) which pre-radiation was SUVmax 8.8 and post-radiation: 9.99. No size is given either time.

    Actually we talked with doc over the phone only yet, they told the disease is stable and there is some minimization which is kinda different as told in CT report. As my dad told about his conversation, the doc want to see a PET/CT again in 3 months. Then tell about further treatment which gonna be chemo if it grows otherwise radiation if stable.

    I have looked through some sites myself and most of them mentioned atleast 3 months of gap between radiation and PET/CT and at minimum it was 6 weeks mentioned at some places.

    Today my dad went to a local oncologist (not our primary) and he suggested to start chemo from next week because as per him it made no sense to waste time since disease is still there. He suggested to go with FOLFOX which we used in 2017 post surgery.

    I don't know about mutations testing or other stuff. My dad's surgery happened in 2017 it was for well differentiated adenocarcinoma. But they never took the sample this time. And our primary doc have strictly advised against the surgery of sacral lesion. I think he sees sacral lesion as major issue than pelvic recurrence.