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PET Scans & False Positives

Posts: 64
Joined: Apr 2011


I wonder if you folks could kindly help me.

My mother had an upper endoscopy and biopsy done, and was diagnosed with esophageal cancer. She is 86 years old and in poor health and the recent cancer diagnosis was devastating news.

When we went to see the Thoracic Surgeon, my mother had not yet had a PET Scan done. The Surgeon therefore spoke to us based on the endoscopy/biopsy results.

After looking at the endoscopy photos, the surgeon mentioned that my mother has a tumor in the middle esophagus. Based on the photos, the surgeon estimated that the tumor was a little under 2 centimeters. However, the surgeon couldn’t tell how deep the tumor was. The surgeon mentioned that it was probably a Stage 3 cancer.

A few days after meeting with the surgeon, my mother had a PET Scan done, and she was referred to an Oncologist. The Oncologist reviewed the PET Scan results. He mentioned that the PET Scan shows that the cancer has spread outside the esophagus, and that it has spread to the lymph nodes above her chest area on both sides of her chest, including the lymph nodes close to the lungs.

However, he said that the cancer has not spread to the lungs or any organs. He said my mother had Stage 4 cancer rather than stage 3, and mentioned that the tumor was approximately 2 centimeters.

Due to my mother’s advanced age and poor health (blood pressure, heart problems, etc.), the oncologist said she should not have surgery. He recommended that she instead have cryotherapy done which he thinks will treat the disease.

However, since the cancer has spread, the oncologist said that my mother should also have chemotherapy done. The Oncologist scheduled my mother for 6 chemotherapy infusions. My mother has had 2 chemo infusions so far and the chemo is seriously damaging her health.

My question is how reliable are PET Scans? I’ve heard that PET Scans can often issue “false positive” readings. I’ve heard that some of the things that can cause a false positive are inflammation, infection, and even healing from a disease.

When my mother had the PET Scan done she was recovering from a terrible cold, which she was suffering from for almost 2 weeks. She was about 80% recovered, and still had a slight cough when she had the PET Scan done. Could this have triggered false positives?

I’ve also heard that after a PET Scan, it’s helpful to have a CT Scan done to confirm the results. My mother did have a CT Scan done a few weeks prior to her endoscopy/biopsy, but the CT Scan was done of her abdomen and pelvis area. The purpose of the initial CT Scan was to verify that there was nothing wrong with her gall bladder, liver and stomach rather than to examine her esophagus. Another CT Scan was not done after the PET Scan was completed.

Given that my mother had not fully recovered from her cold and still had a slight cough when she did the PET Scan, could that have caused false positives? And should they have done a CT Scan to confirm the PET Scan results? I’m hoping that the PET Scan issued false positives so that she can discontinue the chemo which is seriously damaging her health, and instead simply start the cryotherapy.

Any assistance you can provide me in this regard would be deeply appreciated.

Thank you very much for your kind help!!!


Callaloo's picture
Posts: 147
Joined: Nov 2010

Sorry about your mother Tom. I can tell you that a CT scan might not be able to confirm or rule out cancer either, when you're dealing with lymph nodes. If the lymph nodes show up as enlarged on the CT, it could also be from infection, inflammation or cancer. I just went through this -- had a series of 3 CT scans while keeping lymph nodes under observation. They grew, then stopped growing, then grew again. At first we thought they were nothing.

The only way to confirm is do a fine needle biopsy. If the nodes are close to the surface, this is a relatively minor procedure, and can be done by an interventional radiologist rather than a surgeon.

Cindy Bear
Posts: 570
Joined: Jul 2009

Sorry to hear about your mom. Cancer does suck. I know a little about pet scans and I'll share what I know. Yes there can be false positives/negatives with any test... and Pet scan is no different. The pet scan measures cell activity while the cat scan measures structure/growth. The pet measures something called SUV= standard uptake volume. My mother's dr. likened it to a geiger counter, the theory being that more active cells i.e. cancerous cells will take up more of the radioactive glucose and give off higher SUV measurements. We were told anything over 2.7 was deemed malignancy.. but again, no test is perfect.
Good luck to you and your mom.

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