The first step in staging is to examine the patient and find signs or symptoms that indicate local or distant dissemination of the disease. Findings during the physical examination will also be of help to plan the next steps. This will avoid examinations that will not contribute to the staging process and finally shorten the time between presentation and start of treatment. Signs of collateral blood flow and elevated central venous pressure will urge the physician to order vascular contrast examinations, sometimes combined with placement of an expandable vascular stent. The appearance of enlarged lymph nodes in the supraclavicular region will indicate at least an N3 status. Signs of Horners’ syndrome (unilateral ptosis, myosis, enophthalmus, and reduced sweating) or pain in one shoulder or arm indicates involvement of the cervical plexus by invasion of the tumor. A low position of the diaphragm or reversed movement during respiration is indicative of severe COPD or involvement of the phrenic nerve. Diminished breath sounds and dullness at percussion are indicators of pleural effusion, atelectases, or consolidation of a part of the lung. The appearance of lymph nodes in the axilla or subcutaneous metastases will upstage the patient to stage IV disease when malignant cells are found at fine-needle biopsy. Additional CT or PET scans can be omitted in these cases.

Clinical signs of cyanosis, weight loss, paraneoplastic syndromes, comorbidities, low-performance status, medication use, and the psychological condition of the patient are important factors in the process of final treatment planning.

Information obtained from a standard chest X-ray (PA and lateral view) will be the first step in imaging studies. Localization of the primary disease and presence of atelectases or pleural effusion will help to decide on the next investigation. Although less frequently used nowadays, fluoroscopy can be of help to identify superimposed lesions, pleural lesions, a reversed movement of the diaphragm, or stenosis of one of the central airways by movement of the mediastinum during forced inspiration.

Computed tomography is the examination of choice to determine the anatomical landmarks of the tumor and to obtain information about any possible mediastinal lymph node involvement. The extent of the primary tumor can be determined, and the size of the tumor can be measured. Not always a clear discrimination can be made between actual growth into surrounding tissues, as is shown in Fig. 12.2. The appearance of post-obstructive pneumonia or atelectasis can also negatively influence the measurement. Sometimes a PET scan (see below) can be of help. For discrimination of the lymph nodes in the hilar and mediastinal region, contrast-enhanced scans are a requisite. The currently available CT scans are fast and have a high resolution that allows multiplane viewing. Coronal and sagittal images can be constructed in addition to the axial recordings and help to determine whether the primary tumor is invading the mediastinum or other vital structures (Fig. 12.3).

In the following figures, examples of different stages with the plotted anatomical/radiological landmarks are presented.

Positron emission tomography is considered a standard examination for the staging of the early stages of NSCLC. Using fluorodeoxyglucose (FDG), the scan can identify metabolic processes in the body. This tool can discriminate between processes that have a high, low, or absent metabolic activity. When the primary tumor is FDG avid, the sensitivity to detect malignant lymph nodes or distant metastases is very high. The PET scan cannot be interpreted reliably when the primary tumor is not FDG positive or in case of a concurrent infection or other causes (Table 12.1). Concurrent infections occur often in patients with central obstruction by the tumor or due to COPD. Sarcoidosis is one of the well-known diseases that have a high FDG uptake and can mimic a tumor or positive lymph nodes. Therefore, it is important to obtain proof of one of the involved lymph nodes or lesions found in distant sites. The PET scan is not informative on the presence of ingrowth into other structures like the mediastinum when the primary tumor is centrally located. The modern scans combine CT and PET and allow projecting both images on top of each other (Fig. 12.3 and Table 12.2), enabling the physicians to decide on the further diagnostic steps (Fig. 12.4). The combination of CT scan lymph node size and PET activity improves the sensitivity and specificity.