In most cases, lung nodules that appear on CT scans are not indicative of cancer, according to the American Cancer Society. Nodules are more typical of prior infections or scar tissue; however, doctors often investigate nodules to be sure no cancer is present.
To rule out or confirm cancer, CT scans are often repeated to see if nodules are growing, states the American Cancer Society. Depending upon the doctor's level of concern, the scan is typically redone within one month to one year of the first test. A doctor bases the time line on the nodule's size, shape and location. An additional consideration is the nodule's appearance: solid or fluid-filled. Doctors sometimes order PET scans to examine large nodules.
If there is evidence of nodule growth, the doctor does a biopsy, in which he takes a tissue sample of the suspicious nodule, explains the American Cancer Society. A tube with a needle at the end is sometimes eased down the pathway leading to lungs. In other cases, a doctor inserts a needle directly into the chest. If a doctor strongly suspects that a nodule is cancerous, he often removes it surgically.
X-rays are helpful in determining if cancer is present, advises the American Cancer Society. Doctors test coughed-up phlegm for signs of the disease and study the lungs through a bronchoscope, which is a long tube that is inserted down the throat and into the lungs.