Techniques for the Diagnosis of Lung Cancer

Abstract

Lung tumors can grow to large sizes (>3 cm) in an asymptomatic patient because the lung parenchyma lacks innervation for pain perception. Usually, a mass is not discovered until it invades some other structure, such as a blood vessel, a cough receptor, a pleural pain receptor, or a distant site. Accordingly, with the exception of solitary pulmonary nodules seen incidentally on chest roentgenograms, the majority of patients with lung cancer present with symptoms and signs of the tumor. Common symptoms are anorexia, weight loss, cough, hemoptysis, chest-wall or bone pain, fever, hoarseness, shortness of breath, pleuritic pain, and syncope. Physical findings include localized wheezing, which indicates local bronchial obstruction, and decreased breath sounds and dullness over one portion of the lung, signifying effusion, tumor, or collapse. There may also be findings at other sites, including an enlarged liver, lymphadenopathy, superior vena cava obstruction, skin nodules, and clubbing. Any or several of these symptoms and signs stimulate a radiographic search for the cause. Usually a mass, adenopathy, obstructive pneumonia or pleural effusion are seen on a chest X-ray. The clinician’s priority is to determine the anatomical features of the mass or nodule, including size, shape, density, exact location, and relationship to the vital structures. The clinician must then match a reliable, relatively safe diagnostic technique to the patient’s risk profile and tumor anatomy to obtain a histologic specimen. A staging procedure examining the involvement of lymph nodes, local invasion, and distant metastases completes the diagnostic evaluation.