[quote=EricS]With respect, Chris your statements in regards to the PET are so uninformed its painful. Please research this and understand the tests and its shortcomings.

Inflammation, infection, pneumonia will light up a PET among many other conditions . PETs have over a 30% false positive rate and have been the reason for misdiagnosis, unneeded surgeries etc...the ONLY way to identify cancer cells is a biopsy.

I agree that they have many false positives and said so.
I'm proof - we thought I also had lung cancer untill my RO figured out my broken ribs from a motorcycle accident is what was showing in the lung area.

What I said they don't have is false negatives. If there is cancer it WILL show.
Chris

Chris,

Read Charm's posts and realize that a PETs are great for picking up larger tumors...smaller tumors not so much. I've spent 3 years reading everything on my condition, my medications, any and all procedures I've had to have and pay for, which include multiple PETs. The more you read on it, the more you'll understand.

Here's a few excerpts from the American Society of Clinical Oncology's website you may wish to peruse.

"Surprisingly, in the 7 bronchoalveolar cancer cases, only one PET scan was positive with 6 false negative reports (n= 1/7, 14.2%). A bivariate analysis (chi-square with Yate�s correction for continuity) revealed that the PET scan false negatives are significantly higher (p < 0.0000007) for BAL when compared to other types of NSCLC cancers.
Conclusions: PET scanning does not appear to be sensitive in the stagging and detection of BAL lung cancer with sensitivity of 14%"

"Results: Three of 15 residual lesions showed increased SUV, while 12 lesions obtained negative SUV. Three lesions with positive SUV consisted of 2 true-positive and 1 false-positive lesions. Among twelve lesions were negative SUV, 11 lesions were true-negative, and 1 was false-negative. The sensitivity and specificity of FDG-PET in predicting the viability of residual lesions were 66% and 91%, respectively. A lesion of rhabdomyosarcoma which obtained negative SUV in FDG-PET histological showed viable cells. A lesion of another rhabdomyosarcoma which showed positive SUV was evaluated as inflammatory lesion. Conclusions: Although FDG-PET showed excellent sensitivity and fair specificity in predicting the viability of residual lesions in patients with pediatric solid tumors, possibility of false-negativity should give us a caution not to rely on FDG-PET to judge the termination of therapy."

"Results: The overall incidence of confirmed metastatic disease in this study population was 6.0%. Twenty-five (13.5%) of the staging PET scans had areas suspicious for a metastatic lesion(s). Twenty-two patients were further evaluated with subsequent confirmatory imaging and/or biopsy, revealing 10 (45.5%) true positives, and 12 (54.5%) false positives. Of the 157 negative PET scans there was 1(0.5%) false negative and 156 (98.7%) true negatives."

Please READ about the test and do not deal in absolutes. A PET can have a false negative. This site is about providing the "best" information to patients and caregivers. Myself, I try and check any information I post before I post it so I don't lead anyone astray. Respectfully, do the same.

Eric

I misspoke here. Too many late nights. Too many balls in the air. Since this is worth keeping alive, I or one of the monitors will prune off the "new" discussion from the old and start it as a net PET thread because the info is good.

Does everyone agree that we should lock threads that are over 18 months old? Perhaps 24 since that is the period for most recurrences to take place if someone is going to come back to add to their thread. Opinions?

All for it Brian, good idea.

Thank you, Brian. We are dealing with precisely this issue. If J indeed has cancer, the tumor is occult--either too small to show up on a PET scan or has resolved. Either of these scenarios are commonly known to happen. It doesn't mean J doesn't have cancer.

J's initial PET scan lit up bi-laterally for neck nodes. However, a bilateral neck biopsy was not performed. Since he had been very sick with throat infections and allergic reactions just prior to the PET, it was not reliable. Instead of BX'ing the sites that lit up, the RO based the TX protocol on the PET results. That was a dangerous and destructive assumption. J has a new ENT and he will review path reports and most likely order scans. I have also found him a new RO. Incidentally, last week J's MO mailed him an excerpt from his chart clearly stating that the level two node positivity was not diagnostic of malignancy. Hummmm..a CYA maneuver? I'm sure he wants nothing to do with a faulty TX protocol.

A scan shows where to look for cancer...a biopsy is the only definitive procedure to determine that something is or isn't cancer. And...just because we can't see it, doesn't mean it isn't there.

[quote=chrisclu]

What I said they don't have is false negatives. If there is cancer it WILL show.
Chris
[/quote]

Chris: Typing an incorrect statement in bold and capitals DOES NOT MAKE IT TRUE. We're all glad your RO was able to tell that the Petscan gave you a false positive on your ribs. But it's simply not true that a PETscan will always show cancer.
We can all have our opinions here on OCF about lots of things, but you can not make up your own facts. The fact is that Petscans only measure sugar intake, and if the sugar intake of the recovering cells or injuries is higher than the tumor's intake, then the tumor will not show up as cancer.
I'm a nag about this because your statement has enough truth in it that it's believable and will therefore misinform OCF readers.
I'm not going to go into a detailed discussion about tumor hypoxia being one of the main drivers of PETscan accuracy pre treatment but there are many contributing factors that render a Petscan less than optimal for detecting tumor recurrence.
A more accurate statement would be: if your cancer tumor has come back, a Petscan may not identify it especially when it is still small and you have had radiation or chemotherapy within the last year.
I wish Petscans were magical but they are not. I learned this the hard way and then did the "book learning" to find out why.
Charm

I personally know of 2 friends that have had cancer where the PET scan did not light up. One friend had oral cancer and the other one had breast cancer. Both were very early stage I.

I'm sorry. All I know is that I'm glad I had the PET before the lymph nodes were removed. It showed the source was tonsil and allowed me to start radiation rather than the neck disection.
My understanding was that any cancer cells would light up. I thought it was CTs that only showed larger tumors and not small ones.
Anyway. I won't be commenting on PETs anymore.

Chris