Lymph node staging by means of positron emission tomography is less accurate in non-small cell lung cancer patients with enlarged lymph nodes: analysis of 1,145 lymph nodes.
BACKGROUND
Despite documented superiority of integrated positron emission tomography-computerized tomography (PET-CT) over computerized tomography (CT) in lymph node staging in non-small cell lung cancer, little is known about the sensitivity, specificity and accuracy of integrated PET-CT among enlarged lymph nodes. We sought to assess if PET-CT is uniformly accurate among enlarged and non-enlarged lymph nodes.


METHODS
A retrospective review of 206 consecutive patients with histologically proven non-small cell lung cancer who underwent resection and/or mediastinoscopy in our centre over 30 months period was carried out. All these patients had pre-operative staging with integrated PET-CT as an adjunct to chest CT prior to resection and/or mediastinoscopy. Diabetic patients (BM>or=8.0 mmol/l) and those who received neo-adjuvant chemotherapy were excluded. The pathological results of all these cases were reviewed and correlated with those on CT and integrated PET-CT.


RESULTS
The sensitivity, specificity, accuracy, positive and negative predictive values were higher in integrated PET-CT than CT alone in all lymph nodes, whether N1 or N2. When lymph nodes were stratified by size, the sensitivity of PET-CT was significantly higher among enlarged (>1cm) than non-enlarged (<or=1cm) lymph nodes (74% vs. 40%, P<0.0001), but with a significantly lower specificity (81% vs. 98%, P<0.0001) and a lower accuracy (78% vs. 90%, P 0.008).


CONCLUSIONS
Integrated PET-CT remains superior to CT in nodal staging of non-small cell lung cancer. However, in the presence of enlarged lymph nodes, PET-CT becomes less specific, less accurate but more sensitive in detecting metastatic spread to the lymph nodes. Interpretation of PET-CT findings in NSCLC patients with enlarged lymph nodes (>1cm) should be with caution as the specificity of PET-CT is lower and its ability to detect truly negative nodes become reduced. NSCLC patients with enlarged nodes by CT criteria who are PET-CT negative may require cervical mediastinoscopy to rule out metastatic spread to these nodes. Prospective studies are warranted.
Al-Sarraf
Nael
N
Department of Cardiothoracic Surgery, St. James's hospital, Dublin 8, Ireland. Electronic address: trinityq8@hotmail.com.
Gately
Kathy
K
Department of Cardiothoracic Surgery, St. James's hospital, Dublin 8, Ireland.
Lucey
Julie
J
Department of Nuclear Medicine, Blackrock Clinic, Dublin, Ireland.
Wilson
Lorraine
L
Department of Nuclear Medicine, Blackrock Clinic, Dublin, Ireland.
McGovern
Eillish
E
Department of Cardiothoracic Surgery, St. James's hospital, Dublin 8, Ireland.
Young
Vincent
V
Department of Cardiothoracic Surgery, St. James's hospital, Dublin 8, Ireland.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods*; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed