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Lung Cancer

       The lungs are a pair of cone-shaped breathing organs that are found within the chest. The lungs bring oxygen into the body and take out carbon dioxide, which is a waste product of the bodys cells. Each lung has sections called lobes. The left lung has 2 lobes. The right lung, which is slightly larger, has 3 lobes. A thin membrane called the pleura surrounds the lungs. Two tubes called bronchi lead from the trachea (windpipe) to the right and left lungs. The bronchi are sometimes also involved in lung cancer. Tiny air sacs called alveoli and small tubes called bronchioles make up the inside of the lungs.

There are several types of non-small cell lung cancer.
  • Squamous cell carcinoma: Cancer that begins in squamous cells, which are thin, flat cells that look like fish scales. This is also called epidermoid carcinoma.
  • Adenocarcinoma: Cancer that begins in cells that have glandular (secretory) properties.
  • Large cell carcinoma: Cancer in which the cells are large and look abnormal when viewed under a microscope.
  • Adenosquamous carcinoma: Cancer that begins in cells that look flattened when viewed under a microscope. These cells also have glandular (secretory) properties.
  • Pleomorphic, sarcomatoid, or sarcomatous carcinoma: A group of cancers in which the cells look abnormal when viewed under a microscope.
  • Carcinoid tumor: A slow-growing neuroendocrine tumor (cancer that begins in cells that release a hormone in response to a signal from the nervous system).
  • Salivary gland carcinoma: Cancer that begins in salivary gland cells in large airways of the lung.
  • Unclassified carcinoma: Cancer that does not fit into a specific group.
      If the cancer grows into the lumen it may obstruct the airway, causing breathing difficulties. This can lead to accumulation of secretions behind the blockage, predisposing the patient to pneumonia.

      Many lung cancers have a rich blood supply. The surface of the cancer may be fragile, leading to bleeding from the cancer into the airway. This blood may subsequently be coughed up.

      Depending on the type of tumor, so-called paraneoplastic phenomena may initially attract attention to the disease. In lung cancer, this may be Lambert-Eaton myasthenic syndrome (muscle weakness due to auto-antibodies), hypercalcemia and SIADH. Tumors in the top (apex) of the lung, known as Pancoast tumors, may invade the local part of the sympathetic nervous system, leading to changed sweating patterns and eye muscle problems (a combination known as Horner's syndrome), as well as muscle weakness in the hands due to invasion of the brachial plexus.

      In many patients, the cancer has already spread beyond the original site by the time they have symptoms and seek medical attention.