Cancer is a class of diseases characterized by out-of-control cell growth, and lung cancer occurs when this uncontrolled cell growth begins in one or both lungs. Rather than developing into healthy, normal lung tissue, these abnormal cells continue dividing and form lumps or masses of tissue called tumors. Tumors interfere with the main function of the lung, which is to provide the bloodstream with oxygen to be carried to the entire body. If a tumor stays in one spot and demonstrates limited growth, it is generally considered to be benign.More dangerous, or malignant, tumors form when the cancer cells migrate to other parts of the body through the blood or lymph system. When a tumor successfully spreads to other parts of the body and grows, invading and destroying other healthy tissues, it is said to have metastasized. This process itself is called metastasis, and the result is a more serious condition that is very difficult to treat.
Cause of lung cancerSmoking
The incidence of lung cancer is strongly correlated with cigarette smoking, with about 90% of lung cancers arising as a result of tobacco use. The risk of lung cancer increases with the number of cigarettes smoked and the time over which smoking has occurred; doctors refer to this risk in terms of pack-years of smoking history (the number of packs of cigarettes smoked per day multiplied by the number of years smoked). For example, a person who has smoked two packs of cigarettes per day for 10 years has a 20 pack-year smoking history. While the risk of lung cancer is increased with even a 10-pack-year smoking history, those with 30-pack-year histories or more are considered to have the greatest risk for the development of lung cancer. Among those who smoke two or more packs of cigarettes per day, one in seven will die of lung cancer
Asbestos fibers are silicate fibers that can persist for a lifetime in lung tissue following exposure to asbestos. The workplace is a common source of exposure to asbestos fibers, as asbestos was widely used in the past as both thermal and acoustic insulation. Today, asbestos use is limited or banned in many countries, including the U.S. Both lung cancer and mesothelioma (cancer of the pleura of the lung as well as of the lining of the abdominal cavity called the peritoneum) are associated with exposure to asbestos. Cigarette smoking drastically increases the chance of developing an asbestos-related lung cancer in workers exposed to asbestos. Asbestos workers who do not smoke have a fivefold greater risk of developing lung cancer than nonsmokers, but asbestos workers who smoke have a risk that is fifty- to ninetyfold greater than nons
Radon gas is a natural, chemically inert gas that is a natural decay product of uranium. Uranium decays to form products, including radon, that emit a type of ionizing radiation. Radon gas is a known cause of lung cancer, with an estimated 12% of lung-cancer deaths attributable to radon gas, or about 20,000 lung-cancer-related deaths annually in the U.S., making radon the second leading cause of lung cancer in the U.S. As with asbestos exposure, concomitant smoking greatly increases the risk of lung cancer with radon exposure. Radon gas can travel up through soil and enter homes through gaps in the foundation, pipes, drains, or other openings. The U.S. Environmental Protection Agency estimates that one out of every 15 homes in the U.S. contains dangerous levels of radon gas. Radon gas is invisible and odorless, but it can be detected with simple test kits.
The presence of certain diseases of the lung, notably chronic obstruction pulmonary diseases (COPD), is associated with an increased risk (four- to sixfold the risk of a nonsmoker) for the development of lung cancer even after the effects of concomitant cigarette smoking are excluded.
Air pollution from vehicles, industry, and power plants can raise the likelihood of developing lung cancer in exposed individuals. Up to 1% of lung cancer deaths are attributable to breathing polluted air, and experts believe that prolonged exposure to highly polluted air can carry a risk for the development of lung cancer similar to that of passive smoking
While the majority of lung cancers are associated with tobacco smoking, the fact that not all smokers eventually develop lung cancer suggests that other factors, such as individual genetic susceptibility, may play a role in the causation of lung cancer. Numerous studies have shown that lung cancer is more likely to occur in both smoking and nonsmoking relatives of those who have had lung cancer than in the general population. Recently, the largest genetic study of lung cancer ever conducted, involving over 10,000 people from 18 countries and led by the International Agency for Research on Cancer (IARC), identified a small region in the genome (DNA) that contains genes that appear to confer an increased susceptibility to lung cancer in smokers. The specific genes, located the q arm of chromosome 15, code for proteins that interact with nicotin and other tobacco toxins (nicotinic acetylcholine receptor genes).
Symptoms and Warning Signs
Unfortunately, the symptoms of lung cancer can take many years to develop which often leads to diagnosis at an advanced stage of this disease. Some of the symptoms that may occur include:
- Smoker's cough that persists or becomes intense.
- Persistent chest, shoulder, or back pain unrelated to pain from coughing.
- Increase in volume of sputum.
- Nonsmoker's cough that persists for more than 2 weeks.
- Change in color of sputum.
- Blood in sputum.
- Repeated episodes of pneumonia or bronchitis.
Other symptoms that can be related to late-stage lung cancer can include:
- Loss of appetite.
- Headache, bone pain, aching joints.
- Bone fractures not related to accidental injury.
- Neurologic symptoms, such as unsteady gait and/or episodic memory loss.
- Neck and facial swelling.
- Unexplained weight loss.
Other signs and symptoms may be caused by the spread of lung cancer to other parts of the body, including headaches, weakness, pain, bone fractures, bleeding, or blood clots.
Treatment for lung cancer
surgeryA decision to have surgery depends on the size of the tumour and where it is. During the operation, all or part of the tumour and some healthy tissue around the tumour are removed. Surgery is done under general anesthetic (you will be unconscious) and you will stay in the hospital for several days after the surgery.
Surgery is most commonly used for non-small cell cancers that are still small and have not spread. Surgery is not usually done for small cell lung cancer unless tumours are found at a very early stage, before the cancer has started to spread.
Radiation therapyIn external beam radiation therapy, a large machine is used to carefully aim a beam of radiation at the tumour. The radiation damages the cells in the path of the beam – normal cells as well as cancer cells. In brachytherapy, or internal radiation therapy, radioactive material is placed directly into or near the tumour.
ChemotherapyChemotherapy may be given as pills or by injection. Chemotherapy drugs interfere with the ability of cancer cells to grow and spread, but they also damage healthy cells. Although healthy cells can recover over time, you may experience side effects from your treatment like nausea, vomiting, loss of appetite, fatigue, hair loss and an increased risk of infection.
Targeted therapies use drugs or other substances to block the growth and spread of cancer cells. These drugs are able to attack specific types of cancer cells.
Photodynamic therapy uses a special drug that starts to work when exposed to light. The drug is injected into your bloodstream and absorbed by the cancer cells. When exposed to a high-energy laser light, the drug becomes active and destroys the cancer cells. Photodynamic therapy can be used to treat some cases of early-stage
prevention of lung cancer
By far the largest risk factor for lung cancer is smoking. Studies show that smoking tobacco products in any form is the major cause of lung cancer. People who stop smoking and never start again lower their risk of developing lung cancer or of having lung cancer come back.Many products are available to help people trying to quit smoking, including:
- Nicotine sprays
- Nicotine inhalers
- Nicotine patches
- Nicotine lozenges
- Antidepressant drugs.
- Nicotine gums
The other way to avoid lung cancer is a diet rich in fruit, and possibly vegetables, may help lower the risk of lung cancer, while excessive alcohol consumption may increase the risk of lung cancer. In addition, studies show that people who are physically active may have a lower risk of lung cancer than those who are not, even after taking cigarette smoking into account.
Finally for lung cancer prevention starts with learning about the risk factors for lung cancer. It then involves eliminating or minimizing any of those factors that you can control.
Although many lung cancer risk factors can be avoided, it is important to keep in mind that avoiding risk factors does not guarantee that you will not get lung cancer. Also, most people with a particular risk factor for cancer do not actually get the disease. Some people are more sensitive than others to factors that can cause lung cancer. Talk to your doctor about prevention methods that might be effective for you.