Accuracy of positron emission tomography in identifying hilar (N1) lymph node involvement in non-small cell lung cancer: Implications for stereotactic body radiation therapy.

PURPOSE: To assess the efficacy of preoperative positron emission tomography (PET) to stage the ipsilateral hilum in resected non-small cell lung cancer (NSCLC). METHODS AND MATERIALS: All patients who underwent surgery for NSCLC between 1995 and 2008 were evaluated. Patients who underwent preoperative PET imaging at our institution and had hilar nodal sampling were included. Those whose primary tumors extended to the hilum or who received preoperative chemotherapy or radiation therapy were excluded. All PET studies were interpreted by an attending nuclear medicine radiologist and were scored as positive or negative in the hilum or peribronchial area based on visual analysis alone. A 2-sided Fisher exact test compared patient subgroups. RESULTS: During the time interval, 1558 patients underwent surgery for NSCLC, of whom 484 were eligible for this analysis. The ipsilateral hilum was positive on preoperative PET in 107 patients. The median number of N1 lymph nodes sampled was 4 (range, 1-31). Positive ipsilateral N1 lymph nodes were identified pathologically in 91 patients (19%). Among the 91 patients with involved N1 lymph nodes, 40 were PET positive resulting in a sensitivity of 44%. Among 393 patients without pathologic involvement of hilar lymph nodes, 326 were PET negative resulting in a specificity of 83%. The positive predictive and negative predictive values were 37% and 86%, respectively. CONCLUSIONS: Positron emission tomography appears to have limitations in staging the ipsilateral hilar lymph nodes. Invasive sampling is appropriate if treatment would differ based on the nodal status.

Are discordant positron emission tomography and pathological assessments of the mediastinum in non-small cell lung cancer significant?

OBJECTIVE: Many patients with non-small cell lung cancer have positive mediastinal lymph nodes on preoperative positron emission tomography (PET) but do not have mediastinal involvement after surgery. The prognostic significance of this discordance was assessed. METHODS: This Institutional Review Board-approved study evaluated patients treated with upfront surgery at Duke Cancer Institute (Durham, NC) for non-small cell lung cancer from 1995 to 2008. Those staged with PET with pN0-1 disease after negative invasive mediastinal assessment were included. Mediastinal lymph nodes were scored as positive or negative based on visual analysis of the preoperative PET. Clinical outcomes of the PET-positive and PET-negative cohorts were estimated using the Kaplan-Meier method and compared using a log-rank test. Prognostic factors were assessed using a multivariate analysis. RESULTS: A total of 547 patients were assessed, of whom 105 (19%) were PET positive in the mediastinum. The median number of mediastinal lymph node stations sampled was 4 (range, 1-9). The 5-year risk of local recurrence was 26% in PET-positive versus 21% in PET-negative patients (P = .50). Patterns of local failure were similar between the 2 groups. Distant recurrence (35% vs 29%; P = .63) and overall survival (44% vs 54%; P = .52) were comparable for PET-positive and PET-negative patients. On multivariate analysis, a positive PET was not significant for local recurrence (hazard ratio [HR], 1; P = 1), distant recurrence (HR, 0.82; P = .42), or overall survival (HR, 1.08; P = .62). CONCLUSIONS: Patients with positive mediastinal lymph nodes on preoperative PET, but negative on histologic analysis, are not at increased risk of disease recurrence. Pathologic staging remains the standard.