Lung Cancer is a disease that begins in the tissue of the lungs. The lungs are sponge-like organs that are part of the respiratory system. During breathing, air enters the mouth or nasal passage and travels down the trachea. The trachea splits into two sets of bronchial tubes that lead to the left and right lung. The bronchi branch off into smaller and smaller tubes that eventually end in small balloon-like sacs known as alveoli. The alveoli are where oxygen, carbon dioxide, and other substances are exchanged between the lungs and the blood stream.
The vast majority of Lung Cancer cases fall into one of two different categories:
Non-Small Cell Lung Cancer is the most common type of Lung Cancer, making up nearly 80% of all cases. This type of Lung Cancer grows and spreads more slowly than small cell lung cancer. Non-small cell lung cancer is divided into three different subcategories. Squamous cell carcinoma originates in the thin, flat cells that line the passages of the respiratory tract. Adenocarcinoma begins in the cells that form the lining of the lungs. Large cell carcinomas make up a group of cancers that look large and abnormal under a microscope.
Small Cell Lung Cancer makes up nearly 20% of all Lung Cancer cases. It is associated with cancer cells smaller in size than most other cancer cells. These cells may be small, but they can rapidly reproduce to form large tumors. Their size and quick rate of reproduction allows them to spread to the lymph nodes and to other organs of the body. This type of Lung Cancer is almost always caused by smoking or second hand smoke.
One fourth of all people with lung cancer have no symptoms when the cancer is diagnosed. These cancers are usually identified incidentally when a chest x-ray is performed for another reason. The other three fourths of people develop some symptoms. The symptoms are due to direct effects of the primary tumor; to effects of metastatic tumors in other parts of the body; or to malignant disturbances of hormones, blood, or other systems.
Symptoms of primary lung cancers include cough, coughing up blood, chest pain, and shortness of breath.
A new cough in a smoker or a former smoker should raise concern for lung cancer.
A cough that does not go away or gets worse over time should be evaluated by a health care provider.
Coughing up blood (hemoptysis) occurs in a significant number of people who have lung cancer. Any amount of coughed-up blood should cause alarm.
Chest pain is a symptom in about one fourth of people with lung cancer. The pain is dull, aching, and persistent and may involve other structures surrounding the lung.
Shortness of breath usually results from a blockage in part of the lung, collection of fluid around the lung (pleural effusion), or the spread of tumor through the lungs.
Wheezing or hoarseness may signal blockage or inflammation in the lungs that may go along with cancer.
Repeated respiratory infections, such as bronchitis or pneumonia, can be a sign of lung cancer.
