Lung Cancer

Lung cancer is the malignant transformation and expansion of lung tissue, and is the most lethal of all cancers worldwide, responsible for 1.2 million deaths annually. It is caused predominantly by cigarette smoking, and predominantly affects men, with it being the leading cause of death of men between the ages of 40 and 65. With increased smoking among women, it is now occuring in women but it is less common.[1] While some people who have never smoked do still get lung cancer, this appears to be due to a combination of genetic factors[2] and exposure to secondhand smoke.[3][4] Current research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure to inhaled carcinogens. The most common means of such exposure is air pollution and tobacco smoke. Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Treatments include surgery, chemotherapy, and radiotherapy.

Signs and symptoms

Symptoms that suggest lung cancer include: * dyspnea (shortness of breath)
* hemoptysis (coughing up blood)
* chronic coughing or change in regular coughing pattern
* wheezing
* chest pain or pain in the abdomen
* cachexia (weight loss), fatigue and loss of appetite
* dysphonia (hoarse voice)
* clubbing of the fingernails (uncommon)
* difficulty swallowing
* rapid drop in sodium
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. Common sites of metastasis include the bone, such as the spine (causing back pain and occasionally spinal cord compression), the liver and the brain.