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PET Scan after Surgery or Radiation

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Last Modified: June 10, 2007

Dear OncoLink "Ask The Experts,"

I know a woman who had a lobectomy after being diagnosed with lung cancer. She was told that she did not need adjuvant chemotherapy. She just had a PET scan which showed at least one lymph node that was "glowing". She has been told that the PET should not have been done so soon after surgery and that the "glowing" may be the result of the surgery and not an indication of metastatic cancer. Does this make sense, and if so, how long after surgery should a patient wait to have a PET scan?

Peeyush Bhargava, MD, Chief of Nuclear Medicine at The Michael E. DeBakey VA Medical Center, responds:

A PET scan should be performed at least 4-6 weeks after surgery and 4-6 months after radiation therapy. If performed earlier, inflammation secondary to surgery and radiation can be seen as false positive findings on the PET scan as these are FDG avid or tend to "light up" on the scan.