Lung Cancer Lung cancer is not just one disease but rather a group of diseases. All forms of cancer cause cells in the body to change and grow out of control. Most types of cancer cells form a lump or mass called a tumor. Cells from the tumor can break away and travel to other parts of the body where they can continue to grow. This spreading process is called metastasis.
When cancer spreads, it is still named after the part of the body where it started. For example, if breast cancer spreads to the lungs, it is still breast cancer, not lung cancer. Another word for cancerous is malignant, so a cancerous tumor is referred to as malignant. But not all tumors are cancer. A tumor that is not cancer is called benign.
Benign tumors do not grow and spread the way cancer does. They are usually not a threat to life. A few cancers, such as blood cancers (leukemia), do not form a tumor. Most cancers are named after the part of the body where the cancer first starts. Lung cancer begins in the lungs.
The lungs are two sponge-like organs in the chest. The right lung has three sections, called lobes. The left lung has two lobes. It is smaller because the heart takes up more room on that side of the body. The lungs bring air in and out of the body, taking in oxygen and getting rid of carbon dioxide gas, a waste product. The lining around the lungs, called the pleura, helps to protect the lungs and allows them to move during breathing.
The windpipe (trachea) brings air down into the lungs. It divides into tubes called bronchi, which divide into smaller branches called bronchioles. At the end of these small branches are tiny air sacs known as alveoli. Most lung cancers start in the lining of the bronchi but they can also begin in other areas such as the trachea, bronchioles, or alveoli. Lung cancer often takes many years to develop.
Once the lung cancer occurs, cancer cells can break away and spread to other parts of the body. Lung cancer is a life- threatening disease because it often spreads in this way before it is found. Lung cancer is the leading cause of cancer death for both men and women. During the year 2000 there will be about 164,100 new cases of lung cancer in this country. About 156,900 people will die of lung cancer: about 89,300 men and 67,600 women.
More people die of lung cancer than of colon, breast, and prostate cancers combined. Lung cancer is fairly rare in people under the age of 40. The average age of people found to have lung cancer is 60. If lung cancer is found and treated by surgery early, before it has spread to lymph nodes or other organs, the five-year survival rate is about 42%. However, few lung cancers are found at this early stage.
The five-year survival rate for all stages of lung cancer combined was 14% in 1995, the last year for which we have national data. A risk factor is something that increases a person’s chance of getting a disease. Some risk factors, like smoking, can be controlled. Others, such as a person’s age, can’t be changed. Smoking is by far the leading risk factor for lung cancer. More than 8 out of 10 lung cancers are thought to result from smoking.
The longer a person has been smoking, and the more packs per day smoked, the greater the risk. If a person stops smoking before lung cancer develops, the lung tissue slowly returns to normal. Stopping smoking at any age lowers the risk of lung cancer. Cigar and pipe smoking are almost as likely to cause lung cancer as cigarette smoking. There is no evidence that smoking low tar cigarettes reduces the risk of lung cancer.
Nonsmokers who breathe the smoke of others also increase their risk of lung cancer. Non- smoking spouses of smokers, for example, have a 30% greater risk of developing lung cancer than do spouses of nonsmokers. Workers exposed to tobacco smoke in the workplace are also more likely to get lung cancer. There are other risk factors for lung cancer besides smoking. People who work with asbestos have a higher risk of getting lung cancer. If they also smoke, the risk is greatly increased.
The type of lung cancer linked to asbestos, mesothelioma, often starts in the pleura. This type of cancer is covered in a separate American Cancer Society document. Although asbestos was used for many years, the government has now nearly stopped its use in the workplace and in home products. Besides smoking and asbestos, there are a few other risk factors for lung cancer. These include certain cancer-causing agents in the workplace, radon gas, and lung scarring from some types of pneumonia. Also, people who have had lung cancer in the past have a higher chance of having it again and, as mentioned earlier, the risk of lung cancer increases with age. Some studies have shown that the lung cells of women who smoke may develop cancer more easily than those of men.
Clearly, the best way to prevent lung cancer is not to smoke or be around those who do. Young people should not start smoking, and those who already smoke should quit. Everyone, especially babies and children, should be protected from breathing in other people’s smoke. While some people believe that air pollution is a major cause of lung cancer, the truth is that air pollution only slightly increases the risk. Smoking is by far the more important cause.
Even so, some people who have never smoked or worked with asbestos still get lung cancer. Since we do not know why this happens, there is no sure way to prevent it. Since most people with early lung cancer do not have any symptoms, only about 15% of lung cancers are found in the early stages. Although most lung cancers do not cause symptoms until they have spread, you should report any of the following symptoms to your doctor right away. Often these problems are caused by some other condition, but if lung cancer is found, prompt treatment could extend your life and relieve symptoms.
A cough that does not go away Chest pain, often made worse by deep breathing Hoarseness Weight loss and loss of appetite Bloody or rust-colored sputum (spit or phlegm) Shortness of breath Fever without a known reason Recurring infections such as bronchitis and pneumonia New onset of wheezing When lung cancer spreads to distant organs, it may cause: Bone pain Weakness or numbness of the arms or legs, dizziness Yellow coloring of the skin and eyes (jaundice) Masses near the surface of the body, caused by cancer spreading to the skin or to lymph nodes in the neck or above the collarbone Less often, there are some other clusters of symptoms (called syndromes) that can point to a possible lung cancer. Lately, some new tests to find lung cancer early have been developed. These tests are still being studied and are not yet used on a regular basis. If there is a reason to suspect you may have lung cancer, the doctor will use one or more methods to find out if the disease is really present. In addition, a biopsy of the lung tissue will confirm the diagnosis of cancer and also give valuable information that will help in making treatment decisions.
If these tests find lung cancer, more tests will be done to find out how far the cancer has spread. After taking your medical history and doing a physical exam the doctor might want to do some of the following: Imaging tests: these tests use x- rays, magnetic fields, sound waves or radioactive substances to create pictures of the inside of the body. Some of the imaging tests used to find lung cancer and to see where in the body it may have spread include x-rays, CT scan (computed tomography), MRI (magnetic resonance imaging), PET (positron emission tomography) scans, and bone scans. Sputum cytology: a sample of phlegm (spit) is looked at under a microscope to see if cancer cells are present. Needle biopsy: a needle is placed into the tumor to remove a piece of tissue.
The tissue is looked at in the lab to see if cancer cells are present. Bronchoscopy: a lighted, flexible tube is passed through the mouth into the bronchi. This test can help find tumors or it can be used to take samples of tissue or fluids to see if cancer cells are present. Mediastinoscopy: with the patient asleep, tissue samples are taken from the lymph nodes along the windpipe through a small hole cut into the neck. Again, looking at the tissue under a microscope can show if cancer cells are present.
Bone marrow biopsy: a needle is used to remove a small piece of bone, usually from the back of the hip bone. The sample is checked for cancer cells. Blood tests: certain blood tests are often done to help see if the lung cancer has spread to the liver or bones. There are two major types of lung cancer. The first is small cell lung cancer, or SCLC.
The other is non- small cell lung cancer, or NSCLC. If the cancer has features of both types, it is called mixed small cell/large cell cancer. Small cell lung cancer accounts for about 20% of all lung cancers. Although the cancer cells are small, they can multiply quickly and form large tumors. The tumors can spread to the lymph nodes and to other organs such as the brain, the liver, and the bones.
Small cell lung cancer is usually caused by smoking. Other names for small cell lung cancer are oat cell cancer and small cell undifferentiated carcinoma. Non-small cell lung cancer is the most common type of lung cancer, accounting for almost 80% of lung cancers …