Nineteen cases with synchronous multiple primary cancers studied by ¹⁸F-FDG PET/CT

To evaluate the value of fluorine -18-fuoro-2-deoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in evaluating synchronous multiple primary cancers (SMPC).

Nineteen patients with pathologically-confirmed SMPC were collected. Clinical and ¹⁸F-FDG PET/CT characteristics of these patients were reviewed and analyzed. Maximum standardized uptake value, (SUVmax) of all lesions was measured and difference (Δ)SUVmax between the SUV of two primary tumors in each patient was calculated as: [(the larger SUVmax - the smaller SUVmax)/ the larger SUVmax]×100%.

A total of 38 lesions were identified, which were most frequently located in gastrointestinal tract (n=16), followed by lung (n=10), breast (n=4), kidney (n=4), liver (n=2), pancreas (n=1) and thyroid (n=1). Pathologies of these 38 lesions were 18 adenocarcinomas, 8 squamous cell carcinomas, 4 breast invasive ductal carcinomas, 4 renal cell carcinomas, 2 hepatocellular carcinomas, 1 pancreatic ductal adenocarcinoma and 1 papillary thyroid carcinoma. The mean SUVmax of all lesions was 8.5±6.9, most of them being more than 2.5 (n=30). The mean ΔSUVmax was 57.3%±24.6%, indicating different metabolism of the primary cancers in each patient.

In our center, SMPC most commonly involved the gastrointestinal tract and adenocarcinomas were the most common pathology type. ¹⁸F-FDG PET/CT was useful in the diagnosis of SMPC and the ΔSUVmax indicates different pathological origins of the synchronous cancers.