The lungs, a pair of sponge-like, cone-shaped organs, are part of the respiratory system. The right lung has three sections, called lobes; it is a little larger than the left lung, which has two lobes. Cancers that begin in the lungs are divided into two major types, non-small cell lung cancer and small cell lung cancer, depending on how the cells look under a microscope.
Nonsmall cell lung cancer is more common than small cell lung cancer, and it generally grows and spreads more slowly. There are three main types of non-small cell lung cancer. They are named for the type of cells in which the cancer develops: squamous cell carcinoma (also called epidermoid carcinoma), adenocarcinoma, and large cell carcinoma.
Small cell lung cancer, sometimes called oat cell cancer, is less common than non-small cell lung cancer. This type of lung cancer grows more quickly and is more likely to spread to other organs in the body.
Researchers have discovered several causes of lung cancer–most are related to the use of tobacco.
- Cigarettes. Smoking cigarettes causes lung cancer. Harmful substances, called carcinogens, in tobacco damage the cells in the lungs. Over time, the damaged cells may become cancerous. Cigars and Pipes. Cigar and pipe smokers have a higher risk of lung cancer than nonsmokers. Even cigar and pipe smokers who do not inhale are at increased risk for lung, mouth, and other types of cancer. Environmental Tobacco Smoke. The chance of developing lung cancer is increased by exposure to environmental tobacco smoke (ETS)–the smoke in the air when someone else smokes. Exposure to ETS, or secondhand smoke, is called involuntary or passive smoking. Radon. Radon is an invisible, odorless, and tasteless radioactive gas that occurs naturally in soil and rocks. It can cause damage to the lungs that may lead to lung cancer. People who work in mines may be exposed to radon and, in some parts of the country, radon is found in houses. Asbestos. Asbestos is the name of a group of minerals that occur naturally as fibers and are used in certain industries. Asbestos fibers tend to break easily into particles that can float in the air and stick to clothes. When the particles are inhaled, they can lodge in the lungs, damaging cells and increasing the risk for lung cancer. This exposure has been observed in such industries as shipbuilding, asbestos mining and manufacturing, insulation work, and brake repair. Pollution. Researchers have found a link between lung cancer and exposure to certain air pollutants, such as by-products of the combustion of diesel and other fossil fuels. However, this relationship has not been clearly defined, and more research is being done. Lung Diseases. Certain lung diseases, such as tuberculosis (TB), increase a person’s chance of developing lung cancer. Lung cancer tends to develop in areas of the lung that are scarred from TB.
- Personal History. A person who has had lung cancer once is more likely to develop a second lung cancer compared with a person who has never had lung cancer. Quitting smoking after lung cancer is diagnosed may prevent the development of a second lung cancer.
Common signs and symptoms of lung cancer include: A cough that doesn’t go away and gets worse over time.
- Constant chest pain. Coughing up blood. Shortness of breath, wheezing, or hoarseness. Repeated problems with pneumonia or bronchitis. Swelling of the neck and face. Loss of appetite or weight loss.
To help find the cause of symptoms, the doctor evaluates a person’s medical history, smoking history, exposure to environmental and occupational substances, and family history of cancer. The doctor also performs a physical exam and may order a chest x-ray and other tests. If lung cancer is suspected, sputum cytology (the microscopic examination of cells obtained from a deep-cough sample of mucus in the lungs) is a simple test that may be useful in detecting lung cancer. To confirm the presence of lung cancer, the doctor must examine tissue from the lung. A biopsy–the removal of a small sample of tissue for examination under a microscope by a pathologist–can show whether a person has cancer. If the diagnosis is cancer, the doctor will want to learn the stage (or extent) of the disease. Lung cancer often spreads to the brain or bones. Knowing the stage of the disease helps the doctor plan treatment. Treatment depends on a number of factors, including the type of lung cancer (non-small or small cell lung cancer), the size, location, and extent of the tumor, and the general health of the patient. Many different treatments and combinations of treatments may be used to control lung cancer, and/or to improve quality of life by reducing symptoms.
- Surgery is an operation to remove the cancer. The type of surgery a doctor performs depends on the location of the tumor in the lung. An operation to remove only a small part of the lung is called a segmental or wedge resection. When the surgeon removes an entire lobe of the lung, the procedure is called a lobectomy. Pneumonectomy is the removal of an entire lung. Some tumors are inoperable (cannot be removed by surgery) because of the size or location, and some patients cannot have surgery for other medical reasons. Chemotherapy is the use of anticancer drugs to kill cancer cells throughout the body. Even after cancer has been removed from the lung, cancer cells may still be present in nearby tissue or elsewhere in the body. Chemotherapy may be used to control cancer growth or to relieve symptoms. Most anticancer drugs are given by injection directly into a vein (IV) or by means of a catheter, a thin tube that is placed into a large vein and remains there as long as it is needed. Some anticancer drugs are given in the form of a pill. Radiation therapy, also called radiotherapy, involves the use of high-energy rays to kill cancer cells. Radiation therapy is directed to a limited area and affects the cancer cells only in that area. Radiation therapy may be used before surgery to shrink a tumor, or after surgery to destroy any cancer cells that remain in the treated area. Doctors also use radiation therapy, often combined with chemotherapy, as primary treatment instead of surgery. Radiation therapy may also be used to relieve symptoms such as shortness of breath. Radiation for the treatment of lung cancer most often comes from a machine (external radiation). The radiation can also come from an implant (a small container of radioactive material) placed directly into or near the tumor (internal radiation).
- Photodynamic therapy (PDT), a type of laser therapy, involves the use of a special chemical that is injected into the bloodstream and absorbed by cells all over the body. The chemical rapidly leaves normal cells but remains in cancer cells for a longer time. A laser light aimed at the cancer activates the chemical, which then kills the cancer cells that have absorbed it. Photodynamic therapy may be used to reduce symptoms of lung cancer–for example, to control bleeding or to relieve breathing problems due to blocked airways when the cancer cannot be removed through surgery. Photodynamic therapy may also be used to treat very small tumors in patients for whom the usual treatments for lung cancer are not appropriate.
Patients with non-small cell lung cancer may be treated in several ways. The choice of treatment depends mainly on the size, location, and extent of the tumor. Surgery is the most common way to treat this type of lung cancer. Cryosurgery, a treatment that freezes and destroys cancer tissue, may be used to control symptoms in the later stages of non-small cell lung cancer. Radiation therapy and chemotherapy may also be used to slow the progress of the disease and to manage symptoms. Small cell lung cancer spreads quickly. In many cases, cancer cells have already spread to other parts of the body when the disease is diagnosed. In order to reach cancer cells throughout the body, doctors almost always use chemotherapy. Treatment may also include radiation therapy aimed at the tumor in the lung or tumors in other parts of the body (such as in the brain). Some patients have radiation therapy to the brain even though no cancer is found there. This treatment, called prophylactic cranial irradiation (PCI), is given to prevent tumors from forming in the brain. Surgery is part of the treatment plan for a small number of patients with small cell lung cancer. The side effects of cancer treatment depend on the type of treatment and may be different for each person. Side effects are often only temporary.
- Surgery for lung cancer is a major operation. After lung surgery, air and fluid tend to collect in the chest. Patients often need help turning over, coughing, and breathing deeply. These activities are important for recovery because they help expand the remaining lung tissue and get rid of excess air and fluid. Pain or weakness in the chest and the arm and shortness of breath are common side effects of lung cancer surgery. Patients may need several weeks or months to regain their energy and strength. Chemotherapy affects normal as well as cancerous cells. Side effects depend largely on the specific drugs and the dose (amount of drug given). Common side effects of chemotherapy include nausea and vomiting, hair loss, mouth sores, and fatigue. Radiation therapy, like chemotherapy, affects normal as well as cancerous cells. Side effects of radiation therapy depend mainly on the part of the body that is treated and the treatment dose. Common side effects of radiation therapy are a dry, sore throat; difficulty swallowing; fatigue; skin changes at the site of treatment; and loss of appetite. Patients receiving radiation to the brain may have headaches, skin changes, fatigue, nausea and vomiting, hair loss, or problems with memory and thought processes.
- Photodynamic therapy makes the skin and eyes sensitive to light for 6 weeks or more after treatment. Patients are advised to avoid direct sunlight and bright indoor light for at least 6 weeks. If patients must go outdoors, they need to wear protective clothing, including sunglasses. Other temporary side effects of PDT may include coughing, trouble swallowing, and painful breathing or shortness of breath. Patients should talk with their doctor about what to do if the skin becomes blistered, red, or swollen.
Background information provided by: National Cancer Institute, National Institutes of Health, Bethesda, MD 20892