If a routine physical exam reveals swollen lymph nodes above the collarbone, a mass in the abdomen, weak breathing, abnormal sounds in the lungs, dullness when the chest is tapped, abnormalities of the pupils, weakness or swollen veins in one of the arms, or even changes in the fingernails, a doctor may suspect a lung tumor. Some lung cancers produce abnormally high blood levels of certain hormones or substances, such as calcium. If a person shows such evidence and no other cause is apparent, a doctor should consider lung cancer.
Once a malignant tumor begins to cause symptoms, it is usually visible on an X-ray. Occasionally a tumor that has not yet begun to cause symptoms is seen on a chest X-ray taken for another purpose. A CT scan of the chest may be ordered for a more detailed look.
Though tests of mucus or lung fluid may reveal fully developed cancer cells, diagnosis is usually confirmed through a biopsy. Using bronchoscopy, the patient lightly anesthetized, the doctor guides a thin, lighted tube through the nose or mouth and down the air passages to the site of the tumor, where a tiny tissue sample can be removed. Another procedure uses a CT scan to guide a needle into an abnormality in order to take a biopsy. If the biopsy confirms cancer, other tests will determine the type of cancer and how far it has spread. Nearby lymph nodes can be tested for cancer cells, using a procedure called a mediastinoscopy, which requires general anesthesia, and involves having a small cut made in the front of the neck to pass a hollow, lighted tube into the chest to take biopsies. Endobronchial ultrasound and endoscopic esophageal ultrasound are two other ways to biopsy lymph nodes to test for cancer cells. Both require light anesthesia. Imaging techniques such as CT, MRI, PET, and bone scans can detect cancer that may have spread.
Because sputum tests and chest X-rays have not proved particularly effective in detecting small tumors characteristic of early lung cancer, annual chest X-rays for lung cancer screening are not recommended. However, groups such as the American Cancer Society and the National Cancer Institute say CT screening should be offered to those at high risk of lung cancer. That includes smokers and former smokers ages 55 to 74 who have smoked for 30 pack-years or more and either continue to smoke or have quit within the past 15 years. A pack-year is the number of cigarette packs smoked each day multiplied by the number of years a person has smoked. Their guidelines are based on research that showed CT screening decreases the chance of death overall but increases the chance of having a false alarm that requires more testing.