Overview, Causes, & Risk Factors
Primary lung cancer is a very serious respiratory disorder that begins in the airways and air sacs of the lungs.
What is going on in the body?
Cancer of the lung can begin in the lining of the trachea, the smaller airways, and the tiny air sacs. There are different types of lung cancer. Non-small cell lung cancer, or NSCLC, accounts for 70% to 80% of lung cancers. Small cell lung cancer or oat cell carcinoma, or SCLC, accounts for 25% of lung cancers. Both types can be fatal. They invade surrounding tissue and can spread to other parts of the body through the lymph nodes and bloodstream.
Lung cancer is the most common and most deadly cancer in the US. Roughly 160,000 deaths occur each year. Men and woman are equally affected. Most types of lung cancer are aggressive, spreading early in their course. Lung cancer can cause life threatening complications in the chest and spread to distant sites throughout the body causing death in this way. A person also may have symptoms which are reactions to tumors or a substance they make, called a paraneoplastic syndrome.
What are the causes and risks of the disease?
Inhaling tobacco smoke probably causes at least 90% of all lung cancer. Smokers have more than 30 times the risk of nonsmokers. A person’s risk for lung cancer depends on how many packs of cigarettes he or she smokes each day and for how many years. People who quit smoking remain at risk, sometimes for decades. People exposed to radiation, radon, asbestos, and probably heavy metal are also at risk.
Lung cancer occurs if the cells lining the airways of the lungs are constantly exposed and stimulated by cancer-causing substances over several decades. This changes the genetic DNA, makeup of cells and results in the uncontrollable growth of abnormal cells.
It is very rare for a person who has not been exposed to cigarette smoke or radiation to develop small cell lung cancer. It occurs most often in middle aged and elderly people who have been exposed to cancer-causing poisons for several decades.
Symptoms & Signs
What are the signs and symptoms of the disease?
Symptoms of lung cancer include:
A person with this disease may also have:
Sometimes the disease has spread by the time it is diagnosed. If so, symptoms can include:
People often come to the healthcare provider with symptoms of bone pain, pneumonia, enlarged, hard, mostly painless lymph nodes, an enlarged liver and jaundice. Listening to the heart, the doctor may find dullness, loss of breath sounds, a pleuritic rub or a sound caused by an irritated lung lining, and wheezing. The person’s skin may be bluish, and the tips of his or her fingers may be abnormally enlarged.
Lung cancer also can cause many serious problems ranging from paralysis to heart failure.
Diagnosis & Tests
How is the disease diagnosed?
The disease is diagnosed by taking a tissue sample of the lung. There are many ways to collect a tissue sample. Biopsies are obtained wherever the cancer is most accessible. Needle puncture, brush or pinch biopsy is frequently all that is needed. Various ways to collect tissue include:
Through this tissue sample, doctors can tell if the cancer is small cell or non-small cell. Small cell is an aggressive lung cancer deriving from the neuroendocrine cells. It usually has spread cancer cells throughout the body at the time of diagnosis. Frequently a bone marrow biopsy is performed to see if it has spread to the bones. Staging for small cell lung cancer is generally divided into limited disease versus extensive disease.
Non-small cell lung cancer can include all kinds of different cells. Some are flat and scaly, while other disguise themselves as lung cells. These cancers are categorized or staged differently than small cell because this type of lung cancer may be curable. In order to evaluate whether removing all or part of the lung may be feasible, more tests are needed. This includes blood tests, MRI scan of the chest, and bronchoscopy. Other tests, including a bone scan, liver scan or CT scan, may also be needed.
Diagnostic staging is somewhat complex.
At many times exact staging is not known until the chest is opened for surgery.
Prevention & Expectations
What can be done to prevent the disease?
This best way to prevent this cancer is not to smoke and to avoid exposure to second-hand smoke. People who want to quit smoking can try:
Educating young people about the dangers of smoking is a key preventive strategy.
Radon is a cancer-causing substance that should also be avoided. It is sometimes found in the home. If present, it can be reduced to acceptable levels by various means, such as caulking and creating more ventilation.
Early diagnosis may help in reducing some deaths, however, lung cancer tends to spread early. There are no reliable screening blood tests or sputum tests, and screening chest X-rays have not been shown to be cost effective on a population-wide basis.
What are the long-term effects of the disease?
Stage I cancers are considered curable by surgical removal 50 to 90% of the time.
Stage II are curable, but less than 50% of the time. Curability drops off rapidly in later stage disease.
People with stage III-B and IV have an average survival of less than 1 year.
Small cell lung cancer with bulky metastatic disease has a survival of less than 1 year as well. Some patients with grossly limited small cell lung cancer can survive for more than 2 years with aggressive treatment with combination chemotherapy and radiation therapy.
What are the risks to others?
Others are not put at risk since this type of cancer is not considered contagious. People who continue to smoke expose others to the toxic substances in second hand smoke. Radon is a risk factor for any type of lung cancer. Asbestos has been linked to some non-small cell lung cancers.
Treatment & Monitoring
What are the treatments for the disease?
Small cell lung cancer spreads throughout the body. It is sensitive to chemotherapy and radiation therapy. Surgery to remove the cancer where it started is usually not helpful. Multiple agent chemotherapy is given with limited or extensive small cell lung cancer. Response rates are good and some complete remissions are attainable. Chemotherapy is often followed or sandwiched with radiation therapy to the primary cancer site. Radiation to the brain has been used with small cell lung cancer because this is where it often spreads, even after treatment has been finished. Chemotherapy drugs that are used include
Limited stage non-small cell, such as stage I and II cancer, are considered curable. Treatment includes the partial removal of the lung and the removal of lymph nodes in the chest cavity. This is followed up with radiation therapy. Chemotherapy in addition to the radiation may or may not be helpful. Pre- or postoperative chemotherapy have been given along with complete surgical removal. People with higher stages of cancer are not likely to benefit from extensive surgery. They are treated with radiation and/or chemotherapy to relieve symptoms and make them comfortable. Radiation therapy can be given from the outside of the body or through the windpipe. Chemotherapy drugs that have given response include
People who’s cancer has spread to the brain may benefit from whole brain irradiation and corticosteroids to reduce brain swelling. Radiation and/or chemotherapy may relieve other symtoms including painful enlarged liver, bone pain caused by metastases from the lung cancer, or general failing health.
Fluid in the chest containing cancerous cells is treated with needle or chest tube drainage followed by instillation of chemotherapy into the space within the chest that holds the lungs. This will dry up any fluid and improve symptoms. Normal lung is very sensitive to radiation damage, so a complete lung cannot be exposed to radiation. Experimental therapies are desirable for treatment of all stages of this disease since it has been so common and highly lethal. Additional information will benefit the hundreds of thousands of people who have yet to develop this disease. People with this disease often suffer from too much calcium in the blood. It is treated with corticosteroids, diphosphonate medicine, or primary treatment of the cancer.
A team of medical experts is often needed to manage lung cancer. This includes thoracic surgeons, radiation therapists, cancer specialists, lung specialists, and radiologists. Experimental treatments are available at many local, regional, or national institutions. New drugs are being developed and tried in people who have incurable lung cancer. Terminal care can be provided by a hospice-based team.
What are the side effects of the treatments?
When surgery is done to remove part of a lung, it can result in the lung not being able to work. Before surgery, it is important to test the uninvolved lung to see if this can be tolerated. Opening the chest cavity is major surgery, and can have significant illness and even death associated with it.
Side effects of radiation include:
Chemotherapy also has many side effects. The drugs that are used will cause:
People who receive radiation to the brain can have:
Some people may need daily oxygen even if they didn’t before treatment. This disease can recur in spite of all of the above treatments.
What happens after treatment for the disease?
After treatment, people will be followed for lung function, any delayed or prolonged side effects of the treatments, and for recurrence of the disease.
How is the disease monitored?
Monitoring is by frequent visits to the healthcare provider. Physical exams, laboratory tests, chest CT, abdominal CT, and sometimes bronchoscopy are needed. The cancer may return within several months to a few years. People with lung cancer usually have a history of smoking. They remain at risk for development of other tumors, including another lung cancer primary.
Article type: xmedgeneral