Increasing SUV values - 1254285

The last sentence in the blog/post 'FAQ Primer on Pet Scans' states, "Some studies have supported a correlation of cancers with higher uptake (maximum SUV) being associated with a more aggressive clinical behavior, or conversely, low PET uptake with a more indolent clinical behavior of the cancer. In addition, though PET scans are not a standard imaging test for assessing response to therapy (compared with the far more established CT scan), some research suggests that PET scans may provide early feedback about the clinical benefit of lack of benefit from a systemic therapy. However, PET scans also tend to pick up inflammation in the area of recent prior surgery or radiation and are therefore well known to be very difficult to interpret in that setting." found, http://cancergrace.org/cancer-101/2010/09/14/cancer-101-faq-primer-on-p…

The statement about the radiation resonates quite a bit with me. My husband is also followed by PETs and experienced a similar uptick in the SUV after radiation treatment. It took some time to move back down.

Let me know if that helps and don't hesitate to let us know if you have follow up questions. Our search feature is very good though depending on your browser you may need to log out before using it. Also there are many discussions on PET and SUVs in the imaging forums of which there are 2 one in general cancer forums and another in thoracic/lung cancer forums.

Janine
forum moderator

That would really be my inference, but I also really feel that it's hard to consider a cancer as demonstrating clinically significant progression if it isn't increasing in size. We'd definitely prefer to be seeing the SUV go down rather than up over time and treatment, but I and many other experts really feel that it's a mistake to over-interpret a change in SUV in the absence of a change in tumor size. I confess I'd be concerned, but I'd be far more concerned if the cancer were growing as well, and/or there were new areas of disease appearing.

-Dr. West

There's good data for some lymphomas that changes in SUV value can be used to make clinical decisions, but that data isn't there to nearly the same extent in lung cancer. In my practice, size trumpts SUV uptake. In fact, size is so much more useful that I don't routinely get PETs to follow the results of chemo. It's not because I'm trying to save the health care system money (although, perhaps I should mind this more). Rather, it's because non PET CT has higher resolution than the CT obtained during PET/CT. Further, it has contrast. I find that for most patients, the combined increased resolution and IV contrast helps me more in judging stability vs. progression or shrinkage more than the SUV uptakes on PET do. That said, I do use PETs, but for specific purposes--just not as my preferred routine scan type to follow the results of chemo.

I don't order it in this setting, and I would say that there are not recommendations to do PET scans for lung cancer to make clinical decisions about disease progression if a CT scan suggests stability based on the size of existing cancer lesions.

-Dr. West