Positron Emission Tomography/Computed Tomography Thoracic Nodal Staging of Non–Small-Cell Lung Cancer

WSK Cheung

Positron Emission Tomography/Computed Tomography Thoracic Nodal Staging of Non–Small-Cell Lung Cancer
WSK Cheung
Department of Nuclear Medicine, Hong Kong Sanatorium & Hospital, Hong Kong
Correspondence: Dr WSK Cheung, Department of Nuclear Medicine, Hong Kong Sanatorium & Hospital, Hong Kong. Email: William.SK.Cheung@hksh.com
Contributors: The author contributed to the Editorial, approved the final version for publication, and takes responsibility for its accuracy and integrity.
Conflicts of Interest: The author has disclosed no conflicts of interest.
Lung cancer is the leading cause of cancer-related death, with the highest incidence and mortality in Hong Kong.[1] Non–small-cell lung carcinoma (NSCLC) accounts for 94% of all lung cancers. For patients with NSCLC, accurate staging paves a determining role in treatment options and predicts survival. 18F-fluorodeoxyglucose positron emission tomography–computed tomography (18F-FDG PET/CT) has a well-established role in staging of NSCLC and is recommended in guidelines of the National Comprehensive Cancer Network,[2] the American College of Chest Physicians,[3] the American College of Radiology Appropriateness Criteria, and the Society of Nuclear Medicine and Molecular Imaging.[4]
The role of 18F-FDG PET/CT in the TNM staging of NSCLC was reviewed for the eighth edition, and no changes were made to the N descriptors.[5] The N categories based on the location of the involved nodes can be used to consistently predict prognosis. For mediastinal nodal staging, 18F-FDG PET/CT has higher accuracy than CT alone with nodes of >1 cm in the short axis, and it has a sensitivity of 58%-94% and a specificity of 76%-96%.[6] However, the sensitivity and specificity of FDG-PET vary among studies and centres owing to differences in the criteria for PET positivity and the performance metrics of PET/CT scanners.[7] Few studies have evaluated the accuracy of nodal staging in NSCLC when different diagnostic criteria are applied.
In this issue of the Hong Kong Journal of Radiology, Ng et al[8] conducted a retrospective study to evaluate the diagnostic accuracy of 18F-FDG PET/CT for preoperative thoracic nodal staging of NSCLC. The authors compared 18F-FDG PET/CT with a five-point visual score, the maximum standardised uptake value (SUVmax), and short-axis nodal diameter in the axial plane with histopathology.[8] They found that specificity, accuracy, and positive and negative predictive values were significantly higher for the visual score than for nodal diameter. A predictive model combining visual PET positivity with other parameters, including nodal SUVmax, ratio of node to aorta SUVmax, ratio of node to primary tumour SUVmax, and Hounsfield units, has been shown to improve the positive predictive value, specificity, and overall accuracy of 18F-FDG PET/CT in the preoperative diagnosis of nodal metastases.[9] Thus, the visual score is a simple method with good inter-observer agreement, and has great value in nodal staging when combined with PET positivity and visual semi-quantification. Moreover, Ng et al[8] found that the visual score with a cut-off score of 3 achieved satisfactory areas under the curve values in the receiver operating characteristics curves to T stages, histology, epidermal growth factor receptor status, SUVmax of the primary tumour, and nodal stations. This implies the applicability of the visual score in patients with NSCLC.
In conclusion, accurate TNM staging is important to the direct management of NSCLC and bears prognostic implications for patients with NSCLC. 18F-FDG PET/CT is currently the standard of care. Thoracic nodal staging is particularly important for early NSCLC in determining curative surgery. This retrospective local study proposed a simple visual scheme for nodal staging which has high accuracy and good interobserver agreement, and thus can alleviate the robust semiquantitative assessment and application of diagnostic criteria among different scanners.
1. Hospital Authority. Hong Kong Cancer Registry 2019. Overview of Hong Kong Cancer Statistics 2020. Available from: https://www3.ha.org.hk/cancereg/pdf/overview/Overview%20of%20HK%20Cancer%20Stat%202020.pdf. Accessed 13 Nov 2022.
2. Ettinger DS, Wood DE, Aisner DL, Akerley W, Bauman JR, Bharat A, et al. Non–small-cell lung cancer, version 3.2022, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Canc Netw 2022;20:497-530. Crossref
3. Silvestri GA, Gonzalez AV, Jantz MA, Margolis ML, Gould MK, Tanoue LT, et al. Methods for staging non–small-cell lung cancer: diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2013;143(5 Suppl):e211S-e250S. Crossref
4. Ravenel JG, Rosenzweig KE, Kirsch J, Ginsburg ME, Kanne JP, Kestin LL, et al. ACR Appropriateness Criteria non-invasive clinical staging of bronchogenic carcinoma. J Am Coll Radiol 2014;11:849-56. Crossref
5. Kandathil A, Kay FU, Butt YM, Wachsmann JW, Subramaniam RM. Role of FDG PET/CT in the eighth edition of TNM staging of non-small cell lung cancer. Radiographics. 2018;38:2134-49. Crossref
6. Walker CM, Chung JH, Abbott GF, Little BP, El-Sherief AH, Shepard JA, et al. Mediastinal lymph node staging: from noninvasive to surgical. AJR Am J Roentgenol 2012;199:W54-64. Crossref
7. Schmidt-Hansen M, Baldwin DR, Hasler E, Zamora J, Abraira V, Roqué I Figuls M. PET-CT for assessing mediastinal lymph node involvement in patients with suspected resectable non-small cell lung cancer. Cochrane Database Syst Rev. 2014;2014(11):CD009519. Crossref
8. Ng KS, Ng KK, Chu KS, Kung BT, Au Yong TK. Diagnostic accuracy of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in preoperative mediastinal/extramediastinal nodal staging of non–small-cell lung carcinoma. Hong Kong J Radiol. 2023;26:6-13. Crossref
9. Mathew B, Purandare NC, Pramesh CS, Karimundackal G, Jiwnani S, Agrawal A, et al. Improving accuracy of 18F-fluorodeoxyglucose PET computed tomography to diagnose nodal involvement in non–small-cell lung cancer: utility of using various predictive models. Nucl Med Commun. 2021;42:535-44. Crossref