Lung cancer is a disease of uncontrolled cell growth in tissues of the lung. This growth may lead to metastasis, which is the invasion of adjacent tissue and infiltration beyond the lungs. The vast majority of primary lung cancers are carcinomas of the lung, derived from epithelial cells.
Lung cancer, the most common cause of cancer-related death in men and also the most common in women, is responsible for 1.3 million deaths worldwide annually. The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss.
The main types of lung cancer are small cell lung carcinoma and non-small cell lung carcinoma. This distinction is important, because the treatment varies; non-small cell lung carcinoma (NSCLC) is sometimes treated with surgery, while small cell lung carcinoma (SCLC) usually responds better to chemotherapy and radiation. The most common cause of lung cancer is long-term exposure to tobacco smoke. The occurrence of lung cancer in nonsmokers, who account for as many as 15% of cases, is often attributed to a combination of genetic factors, radon gas, asbestos, and air pollution, including secondhand smoke.
Lung cancer may be seen on chest radiograph and computed tomography (CT scan). The diagnosis is confirmed with a biopsy. This is usually performed via bronchoscopy or CT-guided biopsy. Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Possible treatments include surgery, chemotherapy, and radiotherapy. With treatment, the five-year survival rate is 14%.
CAUSES
Lung cancer is more common in older adults. It is rare in people under age 45.
Cigarette smoking is the leading cause of lung cancer.
The more cigarettes you smoke per day and the earlier one started smoking, the greater his/her risk of lung cancer. There is no evidence that smoking low-tar cigarettes lowers the risk.
However, lung cancer has occurred in people who have never smoked.
Secondhand smoke (breathing the smoke of others) increases your risk of lung cancer. According to the American Cancer Society, an estimated 3,000 non-smoking adults will die each year from lung cancer related to breathing secondhand smoke.
The following may also increase one's risk of lung cancer:
· High levels of air pollution High levels of arsenic in drinking water
· Radon gas
· Asbestos
· Family history of lung cancer
· Radiation therapy to the lungs
· Exposure to cancer-causing chemicals such as uranium, beryllium, vinyl chloride, nickel chromates, coal products, mustard gas, chloromethyl ethers, gasoline, and diesel exhaust
SYMPTOMS
Symptoms that suggest lung cancer include:
· shortness of breath
· coughing up blood
· chronic coughing or change in regular coughing pattern
· wheezing
· chest pain or pain in the abdomen
· weight loss, fatigue, and loss of appetite
· hoarse voice
· clubbing of the fingernails (uncommon)
· difficulty swallowing
Many of the symptoms of lung cancer (bone pain, fever, and weight loss) are nonspecific; in the elderly, these may be attributed to comorbid illness. 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 brain, bone, adrenal glands, contralateral (opposite) lung, liver, pericardium, and kidneys. About 10% of people with lung cancer do not have symptoms at diagnosis; these cancers are incidentally found on routine chest radiograph.
TREATMENT
Treatment depends on the specific type of lung cancer.
For non-small cell lung cancer Small cell lung cancer:
· There are many different types of treatment for non-small cell lung cancer:
· Surgery - part or all of the lung is removed
· Radiation therapy - uses powerful x-rays or other radiation to kill cancer cells
· Chemotherapy - uses drugs to kill cancer cells and stop new ones from growing
· Laser therapy - a small beam of light burns and kills cancer cells
· Photodynamic therapy - uses a light to activate a drug in the body, which kills cancer cells
· Watchful waiting - in rare cases, the person may only be monitored until symptoms change
Because SCLC spreads quickly throughout the body, treatment must include cancer-killing drugs (chemotherapy) taken by mouth or injected into the body.
Chemotherapy may be combined with radiation therapy of the lungs in people who have limited disease. The most commonly used drugs in the U.S. are etoposide with either cisplatin or carboplatin. Because the disease has usually spread by the time it is diagnosed, very few patients with SCLC are helped by having surgery. Surgery is only considered when there is only one tumor that has not spread. Chemotherapy or radiation will be needed after surgery.
Combination chemotherapy and radiation treatment is given to people with extensive SCLC. However, the treatment only helps relieve symptoms. It does not cure the disease.
PREVENTION
Prevention is the most cost-effective means of fighting lung cancer. Eliminating tobacco smoking is a primary goal in the prevention of lung cancer, and smoking cessation is an important preventative tool in this process.
Policy interventions to decrease passive smoking in public areas such as restaurants and workplaces have become more common in many countries.
The World Health Organization has called for governments to institute a total ban on tobacco advertising in order to prevent young people from taking up smoking. They assess that such bans have reduced tobacco consumption by 16% where already instituted.
