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DESCRIPTIONPositron emission tomography (PET) scans are based on the use of positron emitting radionuclide tracers coupled to other molecules, such as glucose, ammonia, or water. The radionuclide tracers simultaneously emit 2 high-energy photons in opposite directions that can be simultaneously detected (referred to as coincidence detection) by a PET scanner, consisting of multiple stationary detectors that encircle the area of interest.
A variety of tracers are used for PET scanning, including oxygen-15, nitrogen-13, carbon-11, and fluorine-18. The radiotracer most commonly used in oncology imaging has been fluorine-18 coupled with fluorodeoxyglucose (FDG), which has a metabolism related to glucose metabolism. FDG has been considered potentially useful in cancer imaging, since tumor cells show increased metabolism of glucose.
This policy focuses on the use of PET to determine early treatment response for cancer, that is, assessment of therapy response during cancer treatment. The purpose of the PET scan at this particular interval is to determine whether the treatment being given should be maintained or changed. Such a treatment strategy has been called "risk-adapted" or "response-adapted" treatment. This policy addresses detecting early response during short-term therapy, eg, during cycle(s) of chemotherapeutic agents and/or a course of radiation therapy, and not response during use of long-term agents, such as tamoxifen.
This use is to be distinguished from all uses of PET in the initial diagnosis and staging of cancer, and other uses after treatment such as routine surveillance or detection of recurrence. This is also different from what has been called "response assessment" or "treatment response" in some reports, but clearly refers to imaging done after completion of therapy for the purpose of prognosis and future treatment planning. Some reports differentiate between PET during and after treatment by referring to PET during cancer treatment as "interim treatment response" or "interim staging" and PET at the conclusion of treatment as "restaging."
The technique of using PET for early treatment response assessment involves comparing PET images before treatment and at some interval after the initial course of treatment. Many intervals have been used in various studies, and there appears to be no standard interval. Comparison of the pre-treatment and mid-treatment PET images can either be performed qualitatively or quantitatively. If a quantitative technique is used, a quantity called the standardized uptake value (SUV) is calculated for a specific region of the image. Various methods are used to compare the SUV between the 2 images, and a specific cut-off value is selected to determine whether the patient is responding to therapy. A change in SUV between 40% and 60% has often been used in studies of early treatment response.
Indications for Oncological Applications of PET Scanning are addressed in a separate policy.
POLICYThe use of PET scans to determine early response to treatment (PET scans done during a planned course of chemotherapy and/or radiation therapy) in patients with cancer is considered investigational.
POLICY EXCEPTIONSFederal Employee Program (FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
POLICY GUIDELINESThe coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member’s specific benefit plan language.
There is no specific coding for PET scans to determine early response to treatment. The CPT codes for PET or PET/CT imaging (78811-78816) would be used.
POLICY HISTORY5/20/2009: Policy added
7/16/2009: Approved by Medical Policy Advisory Committee (MPAC)
11/24/2009: Policy Description Section updated with links to related policies, Policy Exceptions Section revised to include FEP verbiage.
02/23/2011: Policy reviewed; no changes.
08/11/2011: Policy reviewed; no changes.
09/27/2012: Policy reviewed; no changes.
10/22/2013: Policy reviewed; no changes.
10/10/2014: Policy title changed from "PET Scanning in Oncology to Detect Early Treatment Response" to "Interim PET Scanning in Oncology to Detect Early Response During Treatment." Policy reviewed; description updated. Policy statement updated to add that PET scans done during a planned course of chemotherapy and/or radiation therapy is considered investigational.
07/30/2015: Code Reference section updated for ICD-10.
SOURCESBlue Cross & Blue Shield Association Policy # 6.01.51
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.