increasing SUV numbers on PET scan

[sunnymom2]

My mom is stage IV nsclc (squamous) dx 6m ago, neversmoker. After round 1 of chemo drugs new mets appeared everywhere so she was switched to Alitma. She has since been on it a few months and had 2 PET scans. Both times they show increasing suv numbers .Her doc has opted to keep her on Alitma, saying sometimes an increasing suv number means 'the cancer is dying off'. He also said the fact no other new mets appeared was a good sign. However every SUV number has increased, ones that were 2.4 are now in the 6.0 range,etc.
Does anyone have any info what increasing SUV means in absence of new mets appearing, should her drugs be switched, kept? Is this success? Thanks.

[ROSH82]

Hi all, I am sincerely sorry to hear about your mum. I dont know how to address these issues ask for all your assistance.

My wife has breast cancer, was discovered in January 2008. We have completed Chemo and radiation. The CT scan before that last showed some nodules in her lung, and the second CT scan confirmed this. The oncologist says that she should go for a PET scan however Discovery would not cover this. Being the husband, I feel so hopeless and less than a man because of this. My wife is just 29 years old and we have 2 kids, the youngest is just 3. I am not sure what this all means, but some sites says that the possiblity of life for 5years  is 14% for lung cancer if it has spread. I would like to know. If you could also tell me how much does the PET scan cost?

[samsonite333]

In order to know if your SUV number is scary or not then you have to know to what SUV the PET scan was normalized to( what is the max SUV).  If you don't know, a PET scan is seen on a computer screen and the SUV number is the brightness of a single particular pixel. A PET scan works like an old black and white TV from the 40's.  If you turn the brightness knob all the way down all youll see is black.  If you start turn the brightness up, white blobs will start appearing signifying possible tumor tissue.  But if you turn the brightness all the way up everything is white!  Online it says if the SUV is 56% of the max SUV it is probably a tumor.  But your doctor may have been talking about your average SUV (mean) basically saying everything looks brighter on the PET scan meaning tumor looking tissue is popping up in more places.  

[Kamal S Saini, MD, MRCP (UK), DM]

Hi,
Sorry to hear of your mothers advanced disease.
The fact that she progressed on first-line chemotherapy, and now has several metastatic lesions, means that her prognosis may not be too good.
Alimta (pemetrexed) has shown modest benefit in such patients.
SUV (standardized uptake value) measures the brightness of the image captured on the PET scan. This brightness, in turn, is dependent on the amount of tracer concentrated in the cancer. The principle is that a highly active cancer nodule will concentrate greater amounts of tracer, which will thus emit greater radioactivity, and thus be captured as a higher SUV.
However, the technology is still evolving, and no difinite 'cut-off' or 'diagnostic' SUV values are universally accepted. Some investigators feel that areas of inflammation (example necrosing or dying cancer nodules) also concentrate the tracer and show high SUVs.
The fact that no new mets have appeared after she started Alimta is a positive sign, and if her previous mets are of the same size means she has 'stable' disease.