Characteristics of Advantages of Positron Emission Tomography over Computed Tomography for N-staging in Lung Cancer Patients

Objective: We analyzed the characteristics of advantages of positron emission tomography(PET) over computed tomography (CT) for N-staging in lung cancer patients.Methods: Preoperative PET and CT scans were performed for 2057 lymph nodestations in205 patients with peripheral-type lung cancer. The advantages of PET over CT for N-stagingwere analyzed among lymph node locations and histological subtypes.Results: The pathological N-stages were N0 in 143 patients, N1 in 31, N2 in 24 and N3in 7. PET was able to diagnose N0, N2 and N3 diseases more accurately than CT (P ¼ 0.03,0.01 and 0.02, respectively), but there was no significant difference between the two modal-ities for N1 disease. In the upper mediastinal lymph node stations, both false-negative andfalse-positive were significantly less frequent with PET than with CT (P ¼ 0.001). In the lowermediastinal and supra clavicle lymph nodes, PET showed a lower frequency of false-negativethan CT (P ¼ 0.04 and 0.003, respectively), but there was no significant difference in the fre-quency of false-positive between the two modalities. Among histological types, PET couldstage adenocarcinoma with less frequent false-negative and squamous cell carcinoma withless frequent false-positive than CT (P ¼ 0.02 and 0.005, respectively).Conclusion: For N-staging, PET was superior to CT for the following: (1) more accurate forN0, N2 and N3 diseases but not for N1; (2) lower frequency of false-positive in the uppermediastinal nodes; and (3) lower frequencies of false-negative in adenocarcinoma and false-positive in squamous cell carcinoma. Recognizing these advantages of PET could make theN-staging of lung cancer more accurate.Key words: positron emission tomography – computed tomography – lymph node stage – lungcancer – adenocarcinoma