Pneumonia can be a sign of lung cancer, according to Everyday Health. A cancerous tumor in the lungs can block off an airway, which can lead to the development of an infection in the area behind the blockage.
Older people should have a chest X-ray after they have pneumonia to check for lung cancer, recommends Everyday Health. This test is particularly important for smokers, who are at increased risk for lung cancer.
Pneumonia or bronchitis that does not respond to treatment can be a sign of lung cancer. Frequent respiratory infections can also be a symptom of lung cancer, as reported by Everyday Health. Other common symptoms of the condition can include persistent chest pain, wheezing, hoarseness and breathing difficulties. People who have lung cancer sometimes cough up blood or sputum. These symptoms can have causes other than cancer, but some doctors recommend that smokers and former smokers who have symptoms should ask their doctors about lung cancer screening.
Once lung cancer spreads beyond the lungs, it can cause swelling in the neck, chest or face, extreme tiredness, difficulty swallowing, headaches, bone pain, and unintended weight loss, states Everyday Health. Another sign of lung cancer is swelling in the fingertips and nails, causing them to resemble round clubs.