Cigarette smoking is the most common cause of lung cancer and results in the common early symptom of persistent coughing, according to the Merck Manuals. Primary lung cancer starts in the lung cells and may develop in airways attached to the trachea, the tube that supplies air to the lungs, or in small air sacs in the lungs. Cancer may also spread to the lungs from other parts of the body.
Coughing
Aside from persistent coughing, lung cancer may also produce a change in the character of the cough for people who have a chronic cough, or "smoker's cough," the Mayo Clinic explains. At times, people may cough up blood. Coughing up even a small amount of blood or sputum with streaks of blood is cause for concern. The bleeding from the cough is not usually severe unless the lung cancer grows into an underlying blood vessel, which is rare, according to Merck. Coughing and other symptoms, especially for smokers, may lead to an early diagnosis of lung cancer and subsequent treatment.
Chest Discomfort
Shortness of breath, fever and chest pain may accompany other symptoms. Fluid may build up in the lungs, increasing the frequency of chest problems. Painful or difficulty swallowing may occur if the lung cancer grows near or at the esophagus. The National Cancer Institute urges people to see a doctor if they have chest discomfort or coughing that won't go away, blood in the sputum, hoarseness, trouble breathing, wheezing, loss of appetite, weight loss or fatigue.
Wheezing
The narrowed airways that cancer causes may result in wheezing or part of the lung collapsing because of airway blockage. Wheezing can occur from infections such as pneumonia or bronchitis, which often signal the early stages of lung cancer. People should pay attention to wheezing if it occurs with persistent coughing and other symptoms.
Diagnosis
Chest X-rays are usually ordered first and can detect most cancers in the lung, according to Merck, though sometimes an X-ray can miss small tumors. Some lung cancers are spotted during X-rays performed for other reasons. A shadow on the X-ray may indicate lung cancer but is not proof. Computed tomography, or CT scans, usually follow X-rays to help doctors verify a diagnosis. A microscopic examination of lung tissue or sample of sputum can also confirm lung cancer. Some people with lung cancer do not have symptoms, and the cancer is found through routine X-rays. Coughing and other symptoms do not necessarily indicate lung cancer and may be from other conditions.
