Lung Cancer Stages
Assessment of Nonsmall Cell Lung Cancer Stages
The medical team will want to know whether the tumor is localized to the lung or whether it has spread to the local lymph nodes or further. A clinical examination would allow a general assessment of lung cancer, and a chest x-ray would supplement this. Performing a CT scan of the chest and abdomen provides a specific anatomical detail to delimitate the primary lung cancer and possible sites of spread. A bone scan may be recommended if there was a suggestion of spread to the bone.
A recently introduced technique called PET scanning (positive emission tomography) is rapidly coming into practice in the standard work-up of patients. The PET scan differs from the CT/MR/ultrasound imaging in that it does not image on anatomic details (e.g. a lump in the liver) but metabolic activity, thus in the usual type of PET scan, the patient is injected with a radioactive analogue of glucose which is concentrated in fast metabolising tissues, such as cancers, and not in scars or other benign problems. The PET image thus discriminates good problems from malignant ones (both within the chest; the first lung mass and the central chest nodes and at distant metastatic sites), and there is a move towards utilizing CT scans and PET scans only in the workup of lung cancer patients.
Where an operation to remove part or the whole of a lung is being contemplated, the surgeon may well wish to perform a rigid bronchoscopy of mediastinoscopy first. In these techniques, and with the patient anaesthetized, a rigid tube is placed down the bronchial tree or mediastinal tissues (in this latter instance, via a small incision at the root of the neck) to assess the local extent of the disease, for example, by biopsying the mediastinal lymph nodes for microscopic analysis.
Imaging investigations and surgical assessment allow nonsmall cell lung cancer to be staged into four categories. Stage 1 and two lung cancers are considered suitable for surgical resection depending on the patients’ fitness and lung function.
Stage 1 lung cancer which is diagnosed in only a minority of patients at their initial workup refers to patients who have the disease of up to 3 cm in diameter within the lung. There must be healthy lung surrounding the lesion and no extension into the primary bronchi feeding the lungs, nor involvement of the lymph nodes in the central chest. This is a potentially highly curable stage.
In the second stage of lung cancer, the tumor in the lung is allowed to be greater than 3 cm and may involve the periphery of the lung (the pleura) or extend up to 2cm from the central division of the trachea into the two main bronchi. There may be involved lymph nodes at the root of the lung but not in the central chest/mediastinal nodes or any evidence of spread further afield.
The third stage (stage 3) refers to patients who have more extensive chest disease but no evidence of disease outside the chest. Where there is disease further afield, the stage is stage 4.
Assessment of Small Cell Lung Cancer
The extent of small cell lung cancer can be assessed by a combination of CT scans and bone scans. For the majority of patients, there is no role for curative surgery, and they should be considered for a combination of chemotherapy and radiotherapy.
In the UK, small cell lung cancer is staged as localized disease or extensive disease. Localized disease refers to patients whose disease is confined to a part of the lung and local lymph nodes only. Extensive disease refers to patients whose disease can be demonstrated beyond the lung and local lymph nodes.