crybaby wrote: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?
I'm very sorry to hear about the increases in size and SUV-uptake in your dad's post-radiation PET-CT scan. It's certainly discouraging to hear this, and I don't know quite what to say. Maybe the scan was done too early after radiation and was still picking up signals from inflammation caused by the radiation itself:
Research Cautions On False Positives For Cancer With PET Scans"However, not all PET-positive lesions are cancer, and in many instances, PET findings can be false positive.".
"...
Inflammatory cells also have increased metabolic rates and, as a result, are FDG avid….”
"...
When seeing a new focus of FDG uptake, before informing the patient that the lesion is cancer, the surgeon and oncologist must determine whether this is truly a cancer or a possible false-positive finding...”
Reference:
https://cancer.stonybrookmedicine.edu/falsepositives
For now, what I think you should do is to try to put this out of your mind for a few days so that you can concentrate on studying for your exam. Then after your exam you could do some reading on false positives on PET-CT scans.
I myself have had some experience with PET-CT false positives. When I was still under treatment, one of my scans showed my left tonsil enlarged, with significant SUV-uptake. The doctor said he was convinced that I had a malignancy in my tonsil. I tried to explain to him that this was probably not the case. I explained that I always sleep on my left side and that my sinuses drain onto my left tonsil, and during allergy season I frequently observe that my left tonsil is much larger than my right tonsil. He wouldn't believe a word of what I was saying, and as a result he scheduled me for a series of costly exams that showed, eventually, that it wasn't cancer after all.
So, I have become rather cynical and skeptical about radiologists' ability to interpret scans correctly, especially when the radiologists are new and inexperienced.
Good luck on your exams !!