With regard to the use of PET scans for selected malignancies, the ICSI Technology Assessment Committee finds the following:
PET scans are safe there are no reports of morbidity or mortality as a result of a PET scan.
The potential for misuse of the technology does exist; PET scans are inappropriate if used a) as a screening tool in the general population, b) when the results would not alter the treatment approach, c) to evaluate neoplasms that are not glucose avid with FDG-PET, d) within 2 months of an operative procedure or within 3-4 months after the completion of treatment, or e) for patients with uncontrolled diabetes or glucose levels above 200 mg/dL.
SPNs: PET scans can correctly distinguish benign from malignant indeterminate SPNs in 87% to 94% of the cases. However, PET scan results do not provide a definitive diagnosis; that is possible only with biopsy and tissue diagnosis. (Conclusion Grade I)
NSCLC: PET is more sensitive, specific, and accurate than CT in evaluating thoracic nodes and extra-thoracic abnormalities for the purpose of staging NSCLC. A negative PET scan may not require invasive follow-up but a positive PET scan should be followed by mediastinoscopy. PET scans have also been found to identify patients not suitable for resection because of distant metastases in 8% to 15% of the cases or N3 disease in 6% of the cases. (Conclusion Grade I)
Recurrent Colorectal Cancer: PET scans may be used to evaluate patients with elevated levels of CEA but negative CT scans. For detection of local recurrence of colorectal cancer, PET scans have been found to be superior to CT scans. For detection of hepatic metastases, PET and CT are at least comparable, but PET provides more information about the extent of disease. Total body PET is superior to CT in identifying extrahepatic disease. Unnecessary operative procedures may be avoided in up to 20% of patients studied. (Conclusion Grade II)
Lymphoma: PET has been found to identify more nodal and more extranodal disease in lymphoma patients. In patients whose disease status has been verified by biopsy, PET scans were more accurate than CT scans for staging. For the evaluation of residual masses, PET scans have been found to be at least as sensitive and more specific than CT. (Conclusion Grade II)
Recurrent Melanoma: PET scans are superior to conventional imaging methods in identifying systemic melanoma metastases with the exception of lung metastases where the various approaches are comparable. Unnecessary operative procedures may be avoided in up to 17% of patients with clinical suspicion of progressive disease. PET scans do not appear to have a primary role in staging regional lymph nodes in patients with localized cutaneous melanoma. (Conclusion Grade II)
To date, there are limited survival data. Randomized controlled trials to determine a survival benefit are not likely. The major benefit of PET scans is in identifying patients who will not benefit from operative resection thereby sparing them from the morbidity and the cost of the procedure. PET scans are also beneficial in determining the optimum treatment strategy for a patient.