Appeal type: Medical necessity
Decision: Upheld

Diagnosis: Cancer 
Treatment: Advanced Imaging. 
The insurer denied positron emission tomography (PET) computed tomography (CT). 
The denial is upheld.  

The patient is a male who underwent an esophagogastroduodenoscopy (EGD) for further evaluation of bloating, heartburn and occult blood loss. The EGD demonstrated a large ulcer at the incisura, biopsy of which demonstrated intramucosal adenocarcinoma. A computed tomography (CT) of the abdomen was performed, which showed no definite gastric mass, although the stomach was only partially distended which limits the ability to determine the presence of a mass. The CT of the abdomen showed no evidence of metastatic disease in the abdomen or the visualized lung bases.
A repeat biopsy was performed. The specimen was labeled "gastric mass", and the diagnosis of "adenocarcinoma, moderately differentiated involving mucosa and extending into muscularis mucosa" was made. The tumor was noted to be present at the deep tissue edge, but no definite submucosal tissue was identified for evaluation.
A positron emission tomography (PET) scan and endoscopic ultrasound were ordered for further evaluation.
The subject under review is the medical necessity for the PET/CT.

The health plan's determination is upheld.

The requested health service, PET CT, is not medically necessary for the patient at the present time, based on the records currently available for review. Clinical staging of gastric cancer is critical for determining the best course of treatment. Staging consists of determining the T stage (the depth of invasion of the cancer into the wall of the stomach), the node (N) stage (whether there is lymph node involvement) and the metastasis (M) stage (whether there is involvement of distant sites).
The initial biopsy performed of the patient's gastric ulcer demonstrated intramucosal carcinoma, otherwise referred to as 'in situ' disease or 'T1s'. This is the lowest stage of gastric cancer and by definition this type of cancer cannot spread. However, this biopsy was performed of what was described as a large ulcer, so there is a reasonable likelihood that the biopsy findings underestimate the depth of invasion and therefore the T stage. A repeat biopsy was subsequently performed, which confirmed that the cancer is indeed invasive into the muscularis mucosa (T1a) and has the potential to spread. However, the biopsy material was insufficient to determine whether the cancer invades deeper than the muscularis mucosa.
A CT of the abdomen performed a few days after the initial biopsy demonstrated that the stomach was only partially distended, so the presence of a gastric mass could not be definitively excluded. However, the CT did not demonstrate any evidence of suspicious lymph nodes or distant metastatic disease.
At this stage of the patient's work-up, the clinical stage of his cancer remains unclear. An endoscopic ultrasound was ordered, which is able to evaluate the depth of invasion of the primary tumor, as well as the status of lymph nodes in the region. Should the endoscopic ultrasound demonstrate that the tumor is indeed a T1a lesion, PET CT scan would not be indicated due to the low likelihood of metastatic disease, especially considering that the CT scan that did not show any evidence of metastatic disease. Further, the accuracy of PET CT in determining the T- stage or N-stage of gastric cancer is lower than that of CT alone. The National Comprehensive Cancer Network Clinical Practice Guidelines for gastric cancer note that PET CT may not be appropriate in the setting of T1 disease, and in fact the best way to determine the T stage in a scenario like this is to perform an endoscopic resection which would be diagnostic and would also be therapeutic if the tumor is indeed a T1 lesion.