Correlation of PET-CT FDG uptake, endobronchial ultrasound cytology and surgical biopsy in patients with Non-Small Cell Lung Cancer undergoing curative surgery.

<bold>Rational:</bold> Mediastinal staging of Non-Small Cell Lung Cancer (NSCLC) is based on the combination of PET-CT and Endobronchial ultrasound (EBUS). However, data regarding the correlation of PET-CT, EBUS cytology and surgical biopsy is scarce. We sought to examine this correlation. <bold>Methods:</bold> 65 NSCLC patients who underwent FDG PET-CT, mediastinal lymph node sampling by EBUS and curative surgery were included. The correlation between PET-CT SUV levels, EBUS cytology and surgical biopsy was assessed. <bold>Results:</bold> 58/67 lymph nodes (86.5%) were negative on EBUS and surgical biopsy; 6 lymph nodes were malignant on EBUS but were negative on surgical biopsy (all 6 patients received neo-adjuvant therapy before surgery); A single lymph node was EBUS negative but was later positive in surgical staging. 2 lymph nodes were malignant on both modalities. Three patients were upstaged due to malignant lymph nodes located at station 5, a location that is inaccessible for EBUS. The distribution of SUV values differed significantly between histology positive and negative lymph nodes sampled by EBUS or surgical staging (P<0.001). No malignant lymph nodes had SUV lower than 2.9. However, 47.1% of normal lymph nodes by EBUS or surgical biopsy had SUV higher or equal to 2.9 (range 0.9-10.1). <bold>Conclusions:</bold> FDG PET-CT ruled out malignancy in lymph nodes with SUV lower than 2.9. On the other hand, for SUV higher than 2.9 PET-CT could not differentiate between malignant and normal lymph nodes. Neo-adjuvant therapy was highly effective as demonstrated by the conversion of malignant lymph nodes by EBUS to normal at surgery.