All cancer diagnoses should and usually do have a tissue diagnosis. A physician get a little piece of tissue from the abnormal mass area and a pathologist determines if it is cancer or not. The two most common methods of getting a piece of the mass is bronchoscopy or fine needle aspiration biopsy under radiologic guidance. Once cancer is diagnosed, an appropriate treatment must be decided upon. The most important determinant is the stage of the cancer.
Stage is how far the tumor has spread.
This can somewhat be determined without surgery, though surgery is needed in many patients for accurate staging. The second important factor is the histologic type of lung cancer. The first two are primarily treated with surgery if the tumor has not spread too far. Oat cell is primarily treated with chemotherapy and has its own separate staging scheme. Radiation therapy is used in both groups of lung malignancies.