Detection of extraoral primary cancers by positron emission tomography/computed tomography in patients with oral squamous cell carcinoma.

Abstract

Extraoral primary cancers (EPCs) can appear in patients with oral cancer. This study investigated the use of positron emission tomography/computed tomography (PET/CT) to detect EPCs and to identify characteristics of these cancers. The disease-specific survival rate and the overall survival rate were calculated. We studied records for 891 patients with oral cancer who underwent PET/CT between January 2006 and December 2016 for the detection of EPCs. A total of 35 EPCs were detected by PET/CT in 34 patients with primary oral carcinoma (3.8%). Of this total, 33 patients had 1 EPC and 1 patient had 2 EPCs. The extraoral lesions were found in the upper gastrointestinal tract (11), colon (6), lung (5), kidney (3), liver (2), prostate (2), breast (2), bladder (1), thyroid (1), pancreas (1), and hypopharynx (1). The disease-specific survival rate was 84.8% and the overall survival rate was 64.6%. PET/CT was useful for early detection of EPCs. The use of PET/CT for the early detection and treatment of EPCs with no symptoms can improve treatment outcomes.