The Role of Fluorodeoxy-D-glucose Positron Emission Tomography/Computed Tomography in Nodal Staging of Nonsmall Cell Lung Cancer in Sequential Surgical Algorithm

Abstract

With nonsmall cell lung cancer (NSCLC), accurate mediastinal nodal staging is crucial to determine whether a patient is or is not a surgical candidate. Traditionally, computed tomography (CT) and fluorodeoxy-D-glucose (FDG) positron emission tomography (PET)/CT are the initial steps followed by tissue sampling through mediastinoscopy and/or thoracotomy, which are invasive procedures. There is controversy regarding the possibility of omission of the invasive diagnostic procedures and solely relying on noninvasive presurgical staging CT and FDG PET/CT results. Eighty-three patients who had PET/CT, mediastinoscopy, and thoracotomy for NSCLC were analyzed. For all lymph nodes that may be sampled by mediastinoscopy, PET/CT sensitivity was 80%, specificity was 86%, positive predictive value was 47%, and negative predictive value (NPV) was 97%; and for those in this group whose clinical stage was T1/T2 M0, sensitivity was 100% and specificity was 84%. For lymph nodes accessible only at thoracotomy, sensitivity was 42% and specificity was 88%. FDG PET/CT is accurate in assessing stations 2R/L, 4R/L, and 7 nodes and has the potential to replace mediastinoscopy in the treatment algorithm of T1/T2 M0 disease. A negative PET/CT may potentially prevent the patient from invasive mediastinoscopy given its high NPV. However, a patient with positive PET/CT should undergo tissue biopsy with pathology confirmation.

Keywords: Fluorodeoxy-D-glucose positron emission tomography/computed tomography; mediastinoscopy; nonsmall cell lung cancer; staging.

Figure 1

False-negative lymph nodes: A 55-year-old female who presented with epigastric pain. Computed tomography revealed a 7.4 cm superior segment right lower lobe lung mass, no pathologically enlarged lymph nodes within the mediastinum or left hilum, no distant metastasis. Positron emission tomography/computed tomography revealed the right lower lobe lung tumor, standardized uptake value 5.5; no active lymphadenopathy; no distant metastasis. Surgical right middle and lower lobectomies, moderately differentiated lung adenocarcinoma, pT3; lymph node metastases ipsilateral stations 2R (5/6), 4R (4/5), and 7-subcarinal (2/3), sizes 0.4 cm and smaller, pN2

Figure 2

False-positive lymph nodes: A 65-year-old male with abnormal chest X-ray showing a right lung nodule, needle biopsy revealed adenocarcinoma. Positron emission tomography/computed tomography revealed a 2.7 cm right upper lobe lung tumor, standardized uptake value 9.6; active lymphadenopathy (arrowheads) in the right lung hilum standardized uptake value 3.1, subcarinal standardized uptake value 3.7, left hilum standardized uptake value 3.2; no distant metastasis. Surgical right upper lobe wedge resection, moderate to poorly differentiated lung adenocarcinoma, pT2; lymph nodes right and left hilar, station 7-subcarinal, benign, chronic inflammation, anthracotic changes, pN0

Figure 3

True-positive lymph nodes: A 47-year-old female with chronic cough and weight loss, chest X-ray showed right hilar lung mass. Positron emission tomography/computed tomography revealed a 2.4 cm right hilar lung tumor, standardized uptake value 5.4; active lymphadenopathy (arrowheads) right mediastinum and subcarinal, standardized uptake value 12. Mediastinoscopy sampled stations 4R (benign), 2R and 7 positive for metastatic nonsmall cell carcinoma