The Role of Positron Emission Tomography/ Computed Tomography (PET/CT) in Staging of Lung Cancer

Background
Lung cancer is the leading cause of cancer-related death. The accurate staging of lung cancer is important in determining the optimal treatment strategy and predicting the prognosis. Positron emission tomography (PET)/computed tomography (CT), which has the advantages of PET and CT and minimizes their limitations, is a potential tool for the staging of lung cancer.


Objective
This study aimed to evaluate the role of PET/CT in the staging of lung cancer.


Patients and methods
This study was carried out on 40 patients with pathologically confirmed lung cancer referred to the Nuclear Medicine Unit affiliated to the Department of Radiodiagnosis at Sharq El Madina Hospital, Ministry of Health, Alexandria, between November 2017 and December 2019 for initial staging of lung cancer with PET/CT or restaging after therapy. Combined PET/CT imaging was performed using the Siemens biograph 64 PET/CT scanner.


Results
(a) Initial staging: PET/CT was able to assess the stage of ten patients (25%), whose stage could not be assessed by CECT. Both PET/CT and CECT disagreed in the staging of six patients. PET/CT staged 10 (25%) patients that could not be assessed by contrast enhanced computed tomography (CECT) and they disagreed in staging of six patients (15%). T staging was predicted by PET/CT in the 40 patients (100%) and by CECT in 30 patients (75%), with disagreement in two patients (5%). PET/CT disagreed with CECT in N staging of 10 patients (25%). PET/CT detected distant metastasis (M) in 18 patients (45%), while CECT detected it in 14 patients (35%). (b) Restaging after neoadjuvant therapy: staging was concordant in six out of eight patients (75%) and dissimilar in two patients (25%).


Conclusion
PET/CT is an essential component in the initial staging of lung cancer for its better locoregional and distant staging abilities. It is also more reliable in restaging after neoadjuvant therapy, being more related to the functional activity of the residual tumor rather than its size.