What is PET2+ or PET2- scan mean?

[brsadmd]

Hello, not an MD here but thought I could consult for some info. What does PET2+ or PET2- scan mean in the terms of cancer treatment? Is there a reference or source for this definition? Because I see many clinical studies use the term but no one defines it. Not even Google gives an answer.

I don't know why my other thread got pulled for a simple question...

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[kraskadva]

First, I'm a M3 and off hand have no idea...

But... on scanning articles that pop up in the 1st page of a google search for "PET2+ scan" it seems that that terminology is whether a PET scan is positive or negative. i.e. a postitive scan is a bad thing = more cancer, where a negative scan is the reverse. (like here - Prognostic value of early 18F-FDG PET scanning evaluation in immunocompetent primary CNS lymphoma patients)

 

[brsadmd]

I see thanks. I guess I was wondering if it meant the cancer actually grew or progressed after 2 cycles, or if failed to respond and stayed the same size.

I also wonder if PET2- means you can still have tumor but it's shrinking and FDG is still more compared to background. But thanks for your input!

 

[kraskadva]

The answer to that is gonna either come from the literature (which I'm not gonna read for you) or an oncologist who does this (which you're unlikely to find in the medical student forum).
So that's an much of an answer as you're gonna get here.

 

[CherryRedDracul]

I see thanks. I guess I was wondering if it meant the cancer actually grew or progressed after 2 cycles, or if failed to respond and stayed the same size.

I also wonder if PET2- means you can still have tumor but it's shrinking and FDG is still more compared to background. But thanks for your input!

As far as I know, PET2+ and PET2- means subsequent PET scans which are positive and negative, respectively.

Definitions can vary as to what the number represent because there is no consistency in its use. It may mean the second PET scan, the third PET scan (if baseline is PET0), or the number may mean the number of courses of chemotherapy.

Whatever paper uses that kind of terminology should define it for you. If not, it's poorly written and the best you can do to get to the bottom of it is to contact the authors for clarification.

 

[brsadmd]

As far as I know, PET2+ and PET2- means subsequent PET scans which are positive and negative, respectively.

Definitions can vary as to what the number represent because there is no consistency in its use. It may mean the second PET scan, the third PET scan (if baseline is PET0), or the number may mean the number of courses of chemotherapy.

Whatever paper uses that kind of terminology should define it for you. If not, it's poorly written and the best you can do to get to the bottom of it is to contact the authors for clarification.

Thanks. I actually also consulted outside. I'm not sure about second or third PET scan but in my case, it means after 2 cycles of chemo, if the PET is positive it means a Deauville score of 4 or 5, The idea is that if you don't respond to chemotherapy by 2 cycles, your prognosis is generally poorer (worse OS, PFS) than someone who is PET2- (someone who responded after 2 cycles and thus, likely to do better).

It can be used to predict how a patient will do after chemo and some studies try to use it as an early diagnostic for how disease plays out. Thank you both for the help.