Background and objective: Lymph node metastases are commonly seen in malignant tumors of the head and neck. Detection of the primary tumors affects the quality of life and survival rates of these patients. This study was to evaluate the application of (18)F-FDG PET/CT in detecting primary tumors metastasizing to lymph nodes of the neck, and to assess the positive predictive value of (18)F-FDG PET/CT.
Methods: In total 93 patients with pathologically confirmed neck lymph node metastases from unknown primary tumors underwent (18)F-FDG PET/CT in Sun Yat-sen University Cancer Center between June 2005 to April 2008 were entered into this study. The primary tumors of patients were initially diagnosed according to different PET/CT standards as definite diagnosis, suspicious diagnosis and no signs of primary tumors. All diagnosis based on PET/CT images were verified by pathological exams or additional imaging tests.
Results: Forty cases made definite diagnosis by PET/CT were all confirmed by pathological or clinical exams, with a positive predictive value of 100%. Of 28 cases made suspicious diagnosis, 16 were pathologically confirmed, with a positive predictive value of 57.1%. Two patients, who were suggested lymph node metastases in mediastinum without the sign of the primary tumor by PET/CT, were clinically verified as primary mediastinal lung cancer. The primary tumors of another two patients were not detected by PET/CT, but were found under endoscopy. The total detection rate of PET/CT for the primary tumor was 60.2% (56/93).
Conclusion: PET/CT is of important clinical value in detecting primary tumors metastasizing to lymph nodes of the neck.