Home > Encyclopedia of Nursing & Allied Health > Lung Cancer

Definition

Lung cancer is a disease in which the cells of the lung tissues grow uncontrollably and form tumors. It is the leading cause of death from cancer among both men and women in the United States. The American Cancer Society estimates that in 2001 at least 169,500 new cases of lung cancer will be diagnosed, and that lung cancer will account for 28% of all cancer deaths—approximately 157,400 people.

Description

Types of lung cancer

There are two kinds of lung cancers, primary and secondary. Primary lung cancer starts in the lung itself. Primary lung cancer is divided into small cell lung cancer and non-small cell lung cancer, depending on how the cells look under the microscope. Secondary lung cancer is cancer that starts somewhere else in the body (for example, the breast or urinary bladder) and metastasizes (spreads) to the lungs. Identifying the type of lung cancer is important because treatment varies by type. For example, small cell cancers generally are treated with surgery. On the other hand, surgery is not generally considered beneficial for non-small cell cancers; they are treated with chemotherapy.

Small cell cancer was formerly called oat cell cancer, because the cells resemble oats in their shape. About a fourth of all lung cancers are small cell cancers. This is a very aggressive cancer and spreads to other organs within a short time. It is generally diagnosed in people who are heavy smokers. Non-small cell cancers account for the remaining 75% of primary lung cancers. They can be further subdivided into three categories.

Nearly 30% of non-small cell cancers are squamous cell carcinomas. Squamous cell carcinoma is most often found near the bronchi of patients with a history of smoking. Forty percent of non-small cell cancers are adenocarcinomas, most often found in the outer region of the lung. The remaining 10% are large-cell undifferentiated carcinomas. These rapidly spreading carcinomas may be found throughout the lung.

Incidence of lung cancer

Lung cancer is rare among young adults. It is usually found in people who are 50 years of age or older, the average age at diagnosis is 60. While the incidence of the disease is decreasing among white men, it is steadily rising among African-American men, and among both white and African-American women. This change is probably due to the increase in the number of smokers in these groups. In 1987, lung cancer replaced breast cancer as the number one cancer killer among women. Lung cancer is responsible for more deaths than the combined totals for cancers of the colon, breast, and prostate.

Causes and symptoms

Causes

SMOKING. Tobacco smoking is the leading cause of lung cancer. Ninety percent of lung cancers can be prevented by giving up tobacco. Smoking marijuana cigarettes is considered yet another risk factor for cancer of the lung. These cigarettes have a higher tar content than tobacco cigarettes. In addition, they are inhaled very deeply—as a result, the carcinogens in the smoke are held in the lungs for a longer time.

EXPOSURE TO ASBESTOS AND TOXIC CHEMICALS.

Exposure to asbestos fibers, either at home or in the workplace, is also considered a risk factor for lung cancer. Studies show that compared to the general population, asbestos workers are seven times more likely to die from lung cancer. Asbestos workers who smoke increase their risk of getting lung cancer by 50-100 times. Besides asbestos, mining industry workers exposed to coal products or radioactive substances such as uranium, and workers exposed to chemicals such as arsenic, vinyl chloride, mustard gas, and other carcinogens also have a higher than average risk of contracting lung cancer.

ENVIRONMENTAL CONTAMINATION. High levels of radon, a radioactive gas that cannot be seen or smelled, pose a risk for lung cancer. This gas is produced by the breakdown of uranium, and does not present any problem outdoors. In the basements of some houses that are built over soil containing natural uranium deposits, however, radon may accumulate to dangerous levels. Other forms of environmental pollution (e.g., auto exhaust fumes) may also slightly increase the risk of lung cancer.

CHRONIC LUNG INFLAMMATION AND SCARRING. Inflammation and scar tissue are sometimes produced in the lung by diseases such as silicosis and berylliosis, which are caused by inhalation of certain minerals; tuberculosis; and certain types of pneumonia. This scarring may increase the risk of developing lung cancer.

FAMILY HISTORY. Although the exact cause of lung cancer is not known, people with a family history of lung cancer appear to have a slightly higher risk of contracting the disease.

Symptoms

Because lung cancers tend to spread very early, only 15% are detected in their early stages. The chances of early detection, however, can be improved by seeking medical care at once if any of the following symptoms appear:

• a cough that does not go away
• chest pain• shortness of breath
• persistent hoarseness
• swelling of the neck and face
• significant weight loss that is not due to dieting or vigorous exercise; fatigue and loss of appetite
• bloody or brown-colored phlegm (sputum)
• unexplained fever
• recurrent lung infections, such as bronchitis or pneumonia

Diseases other than lung cancer may cause these symptoms. It is vital, however, for patients to consult a physician to rule out the possibility that they are the presenting symptoms of lung cancer.

If the lung cancer has spread to other organs, the patient may have other symptoms such as headaches, bone fractures, pain, bleeding, or blood clots. Early detection and treatment can increase the chances of a cure for some patients; for others, it can at least prolong life.

Diagnosis

Physical examination and initial tests

If lung cancer is suspected, the physician will take a detailed medical history to document the symptoms and assess the risk factors. The history is followed by a complete physical examination. The physician will examine the patient's throat to rule out other possible causes of hoarseness or coughing, and listen to the patient's breathing and the sounds made when the patient's chest and upper back are percussed (tapped). The physical examination, however, is not conclusive.

If there is reason to suspect lung cancer—such as a history of heavy smoking or occupational exposure to substances known to irritate the lungs—the physician may order a chest x ray to see if there are any masses in the lungs. Special imaging techniques, such as PET scans (positron emission tomography), CT (computerized axial tomography) scans or MRI (magnetic resonance imaging) may provide more precise information about the size, shape, and location of any tumors. X ray and other imaging techniques may be performed by a radiologic technician.

Sputum analysis

Sputum analysis involves microscopic examination of the cells that are either coughed up from the lungs, or are collected through a bronchoscope. Sputum analyses can diagnose at least 30% of lung cancers, some of which do not show up even on chest x rays. In addition, this laboratory test can help detect cancer in its very early stages, before it metastasizes (spreads) to other regions. The sputum test does not, however, provide any information about the location of the tumor and must be followed by other diagnostic tests.

Lung biopsy

Lung biopsy is the definitive diagnostic tool for cancer. It can be performed in several different ways. The physician can perform a bronchoscopy, which involves the insertion of a slender, lighted tube, called a bronchoscope, down the patient's throat and into the lungs. In addition to viewing the passageways of the lungs, the physician can use the bronchoscope to obtain samples of the lung tissue. In another procedure known as a needle biopsy, the location of the tumor is first identified using a CT scan or MRI. The physician then inserts a needle through the chest wall and collects a sample of tissue from the tumor. In the third procedure, known as surgical biopsy, the chest wall is opened up and a part of the tumor, or all of it, is removed. A pathologist, a physician who specializes in the study of diseased tissue, examines the tumor samples to identify the cancer type and stage.

Patient education

Patients who will undergo surgical diagnostic and treatment procedures should be encouraged to stop smoking. Patients able to stop smoking several weeks before surgical procedures have fewer postoperative complications.

Treatment

Treatment for lung cancer depends on the type of cancer, its location, and its stage. Staging is a process that describes if the cancer has metastasized and the extent of its spread. Lung cancer is staged at the time of diagnosis; this is called clinical staging. It usually is staged again following surgical intervention; this is called pathologic staging. When determining a course of treatment, the patient's age, medical history, and general state of health are taken into account. The most commonly used modes of treatment are surgery, radiation therapy, and chemotherapy.

Surgery

Surgery is not usually an option for small cell lung cancers, because they have usually spread beyond the lung by the time they are diagnosed. Because non-small cell lung cancers are less aggressive, however, surgery can be used to treat them. The surgeon determines the type of surgery, depending on how much of the lung is affected. Surgery may be the primary method of treatment, or radiation therapy and/or chemotherapy may be used to shrink the tumor before surgery is attempted.

Not all patients are candidates for surgery, especially the removal of an entire lung (pneumonectomy). For example, many smokers suffer from emphysema as well as lung cancer, and as a result have sharply reduced lung capacity. Spirometric testing may be performed to assess lung capacity. The forced expiratory volume in one second (FEV1) is a laboratory test that helps to determine whether patients will have adequate pulmonary function after resection.

There are three different types of surgical operations:

• Wedge resection. This procedure involves removing a small part of the lung. A wedge resection is done when the cancer is in a very small area and has not metastasized to any other chest tissues or other parts of the body.
• Lobectomy. A lobectomy is the removal of one lobe of the lung. The right lung has three lobes and the left lung has two lobes. If the cancer is limited to one part of the lung, the surgeon will perform a lobectomy.
• Pneumonectomy. A pneumonectomy is the removal of an entire lung. If the cancer cells have spread throughout the lung, and if the surgeon feels that removal of the entire lung is the best option for curing the cancer, a pneumonectomy will be performed.

Postoperative surgical nursing care includes monitoring temperature, pulse blood pressure and respiration. Fever may indicate infection; patients are vulnerable to bacterial and viral infections. Decreased breath sounds may be symptoms of pneumothorax. The pain that follows surgery can be relieved by medications. The tendency of surgical stress to weaken the patient's immune system is treatable with antibiotics, anti-viral medicines, and vaccines.

Patient education

Postoperative patient teaching encourages ambulation (walking), and reinforces patient and family understanding of surgical results and necessary follow-up.

Radiotherapy

Radiotherapy involves the use of high-energy rays to kill cancer cells. It is used either by itself or in combination with surgery or chemotherapy. Radiotherapy can be used to treat all types of cancer. The amount of radiation used depends on the size and the location of the tumor. There are two types of radiotherapy treatments, external beam radiation therapy and internal (or interstitial) radiotherapy. In external radiation therapy, the radiation

is delivered from a machine positioned outside the body. Internal radiotherapy uses a small pellet of radioactive materials placed inside the body in the area of the cancer.

Radiation therapy may produce such side effects as tiredness, skin rashes, upset stomach, and diarrhea. Dry or sore throats, difficulty in swallowing, and loss of hair in the treated area are all minor side effects of radiation. Some side effects diminish or disappear either during the course of the treatment or after the treatment is over.

Patient education

Patient education by nurses and radiologic technicians includes measures to identify and manage side effects such as fatigue or radiodermatitis (skin condition resulting from radiotherapy).

Chemotherapy

Chemotherapy uses anti-cancer medications that are either given intravenously or taken by mouth. These drugs enter the bloodstream and travel throughout the body, killing cancer cells that have spread to different organs. Chemotherapy is used as the primary treatment for cancers that have spread beyond the lung and cannot be removed by surgery. It may also be used in addition to surgery or radiation therapy.

Chemotherapy is tailored to each patient's needs. The prescribed regimen depends on the type of cancer, the extent of its spread, and the patient's general state of health. Most patients are given a combination of several different drugs. Besides killing the cancer cells, these drugs also harm normal cells. Hence, the dose has to be carefully adjusted to minimize damage to normal cells. Chemotherapy often has severe side effects, including nausea, vomiting, hair loss, anemia, weakening of the immune system, and sometimes infertility. Most of these side effects end when the treatment is over. Other medications can be given to lessen the unpleasant side effects of chemotherapy.

Patient education

Patient teaching helps patients and families to distinguish between anticipated side effects such as alopecia (hair loss), nausea, and constipation and the more serious side effects that require medical attention. Examples of

side effects that can not be managed at home include bleeding, fever, and confusion or hallucinations.

Prognosis

If the lung cancer is detected before it has had a chance to spread to other organs, and if it is treated appropriately, at least 49% of patients can survive five years or longer after the initial diagnosis. Only 15% of lung cancers, however, are found at this early stage.

Improvements in surgical technique and the development of new approaches to treatment have markedly improved the one-year survival rate for lung cancer. Slightly more than 40% of patients survive for at least a year after diagnosis, as opposed to 30% 25 years ago. The five-year survival rate for all stages of lung cancer is 14%.

Health care team roles

Lung cancer treatment involves an multidisciplinary team of health care professionals. In addition to primary care physicians, such as a family practitioner or an internist, the treatment team may include a pulmonologist, pathologist, radiologist, and thoracic surgeon as well as specialized nurses, radiologic and laboratory technicians, respiratory therapists, and dieticians.

Patient education

Before, during and after treatment, nurses and allied health professionals should inform and educate patients and families about the risks and complications of any planned diagnostic test, intervention, or treatment. Patients and families should be taught about some of the common side effects of treatment, including weight loss, malnutrition, increased risk of infection, pain, fatigue, and depression.

Prevention

The best way to prevent lung cancer is never to smoke or to quit smoking if one has already started. Secondhand smoke from tobacco should be avoided. Appropriate precautions should be taken when working with carcinogens (cancer-causing substances). Promoting healthy lifestyles, testing houses for the presence of radon gas, and asbestos abatement are also useful preventive strategies.

Patient education

objectives of education are to prevent patients, especially children and adolescents, from smoking, and to encourage smokers to quit. Participation in smoking cessation programs should be encouraged and patients should be informed about the health risks of passive (secondhand) smoking. Patient education also should describe the role of environmental carcinogens such as asbestos and radon in the development of lung.

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KEY TERMS

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Alopecia—Hair loss.

Biopsy—The surgical removal and microscopic examination of living tissue for diagnostic purposes.

Bronchoscope—A thin, flexible, lighted tube that is used to view the air passages in the lungs.

Carcinogen—Any substance capable of causing cancer.

Chemotherapy—Treatment of cancer with synthetic drugs that destroy the tumor either by inhibiting the growth of cancerous cells or by killing them.

Lobectomy—Surgical removal of an entire lobe of the lung.

Metastasize—The spread of cancer cells from a primary site to distant parts of the body.

Pathologist—A physician who specializes in the diagnosis of disease by studying cells and tissues under a microscope.

Pneumonectomy—Surgical removal of an entire lung.

Pneumothorax—Collapse of the lung.

Radiation therapy—Treatment using high energy radiation from X-ray machines, cobalt, radium, or other sources.

Sputum—Mucus or phlegm that is coughed up from the passageways of the lungs.

Stage—A term used to describe the size and extent of spread of cancer.

Wedge resection—Removal of only a small portion of a cancerous lung.

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Barbara Wexler