Doctors Lounge - Oncology Answers
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Forum Name: Lung Cancer
|lindseyup67 - Wed Sep 16, 2009 7:11 pm|
My mom was diagnosed last Oct. with stage 3a non small cell lung cancer. She had a pnemonectomy,and took no further treatment. Her PET scan results today to check for a reoccurence of the lung cancer revealed that her mediastinal lymph nodes were enlarged 3.0 cm,but her doctor and the person that read the scan do NOT think that it is cancer, they think it is due to recovering from the surgery. I cannot locate any info online that tells me that enlarged lymph nodes can be from postop, most seem to be due to an infection of reoccurence of the cancer. Can this be possible that it is not cancer, after all? Please advise, Lindsey
|Dr.M.Aroon kamath - Tue Nov 24, 2009 8:24 am|
Let me try and explain to you the intricacies involed in the elucidation of a lesion that appears on a PET scan following treatment(primary/adjuvant) of lung cancer.
On imaging, It is important to be aware of normal, benign findings that occur after surgery and/or radiation therapy, and to distinguish such findings from those which may indicate a recurrent tumor.
Following pneumonectomy, the ipsilateral hemithorax normally fills with fluid which gets organized , appearing as low attenuation material on CT imaging.
The presence of a mass within the low attenuation material suggests local tumor recurrence.
Post-radiation pulmonary necrosis is an uncommon,but severe complication of adjuvant post-operative radiation therapy. It manifests as cavitation within a fibrotic space (usually in the apex of the lung ) and occurs 1–7 years following treatment of the primary. Such an appearance may simulate recurrent tumor. The diagnosis is generally by exclusion, usually made after a negative biopsy of the lesion and/or stability on follow-up imaging.
FDG-PET imaging has a role in distinguishing persistent or recurrent tumor from post-treatment scarring or fibrosis. It is more sensitive than CT of the chest in detecting recurrent tumor (sensitivity of 95–100%). However, it has a specificity of 60–100%, sometimes yielding false-positive results due to active inflammation, particularly in the acute post-operative or post-radiation phase.
Therefore, FDG-PET scanning should be obtained no earlier than 4–5 months following radiation therapy.
I have to apologise for being too technical, but,it hopefully gives you an idea how difficult these diagnoses may be!.
Most experts in this field would perhaps tend to base their final diagnosis (on a finding discovered on imaging) by performing a biopsy.
|lindseyup67 - Wed Dec 30, 2009 10:19 pm|
Thanks for your response. For follow up..she never took chemo or radiation therapy, just the pnemonectomy . The CAT scan that she had done in July, and most recently a few weeks ago (Dec.) showed that while the mediastinal lymph nodes are still slightly swollen, they have not changed in appearance nor grown in size since July. Also, these did not "light up" on her PET scan. Would this lead one to believe that these are not cancerous, given these facts? Please advise, Lindsey
|Dr.M.Aroon kamath - Sat Jan 02, 2010 8:59 pm|
False negatives in a PET scan can also occur in tumors with a low metabolism, like carcinoid tumors and bronchioloalveolar cell carcinomas.
Bronchioloalveolar cell carcinomas are a variant of non-small cell lung cancers.
You have not indicated the histological type of tumor your mother was diagnosed with. Was it by any chance a Bronchioloalveolar cell carcinoma?
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