Bronchoalveolar Lung Cancer
Key Terms: Medical oncologist, Pulmonologist, Radiation oncologist.
Definition
Bronchoalveolar lung cancer is a type of non-small cell lung cancer. The World Health Organization (WHO) classifies it as a subtype of adenocarcinoma.
Description
When a person breathes, air enters the trachea (windpipe). In the chest, the trachea splits into two passageways called bronchi. One goes to the right lung and the other to the left lung. The bronchi then subdivide into smaller tubes called bronchioles. These bronchioles end in tiny air sacs called alveoli. A diagram of the respiratory system resembles an upside down tree with the trachea as the tree trunk and the alveoli as the leaves. Exchange of gasses between the lungs and the blood occurs in the alveoli.
Lung cancer, like all cancers, is the result of uncontrolled cell growth. The specific characteristics of each cancer depend on which cells are growing out of control and where they are located. There are two distinct types of lung cancer each with its own characteristics and treatment strategies—small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC).
NSCLC can develop from several different types of lung cells, so it is further categorized as either squamous cell carcinoma, adenocarcinoma, or large-cell lung cancer. Bronchoalveolar lung cancer is a subtype of adenocarcinoma.
Bronchoaveolar lung cancer is a primary malignant cancer of the lungs, meaning that the lungs are the first place this cancer develops; it does not migrate to the lungs from elsewhere in the body. Bronchoalveolar cancer usually develops in the outer (peripheral) regions of the lungs in gland-like cells that secrete mucus. It spreads along the membranes that separates the alevoli from each other.
Research published in 2003 suggests that there are two patterns to the development of bronchoalveolar cancer. In about 40–80% of cases, these cancer cells are found in a limited area of the lung, making surgery a possible treatment. In the remainder of the cases, they are spread out over a wide area. Regardless of how these cells are distributed, they look identical, and they are often mixed in with other adenocarcinoma cells.
Demographics
Lung cancer is leading cause of cancer deaths in the United States. The American Cancer Society predicted about 172,500 new cases of lung cancer (all types) would develop in 2005, accounting for about 13% of all new cancers. Lung cancer occurs primarily in people over age 45, and is slightly more likely to occur in men than in women.
Adenocarcinoma accounts for about 40% of all lung cancers, up from about 13% in 1965. The number of lung cancer cases attributed to adenocarcinoma is increasing rapidly in the United States and Europe, especially in women, although cases are also increasing among men. Bronchoalveolar cancer is thought to account for between 2% and 14% of all cases of lung cancer. About 85% of lung cancers can be attributed to smoking tobacco. However, although smoking cigarettes increases the risk of developing bronchoalveolar cancer, it is the most common type of lung cancer found among individuals who have never smoked cigarettes.
Causes and Symptoms
In general, lung cancers develop because of acquired changes that occur in the genes of lung cells when they are exposed to carcinogens such as tobacco smoke. These changes either turn on genes that cause cells to grow uncontrollably (oncogenes) or turn off genes that cause cells to die at the appropriate time (tumor suppressor genes) or both.
Because bronchoalveolar cancer is the most likely lung cancer to develop among people who have never smoked, its exact cause is somewhat unclear. Like all lung cancers, smoking tobacco or marijuana, exposure to asbestos, and inhalation certain workplace chemicals (e.g. radon gas, arsenic, beryllium, vinyl chloride, coal products, gasoline exhaust) increases the risk of developing bronchoalveolar cancer. However, since this type of cancer is increasing and is common among non-smokers, some other yet to be determined factors seem to play a role in its development.
Lung cancer symptoms tend to develop only after the cancer is far advanced and possibly has even spread (metastasized) to other placed in the body such as the liver, adrenal glands, bones, or brain. Bronchoalveolar cancer is no exception. When symptoms do occur, they include:
- coughing
- difficulty breathing
- chest pain
- weight loss
Bronchoalveolar lung cancer causes the cells lining the lungs to produce a lot of mucus. When examined by a doctor, the lungs may have an abnormal dead or dull sound because of the amount of mucus they contain. Severity of symptoms, however, is not well correlated to the severity or stage of this cancer.
Diagnosis
Diagnostic tests are the same as for any suspected lung cancer, beginning with a chest x ray and moving on to other imaging studies such as computed tomography (CT) scan, magnetic resonance imaging (MRI), ultrasound, and positron emission tomography (PET) scans. Initial tests determine the presence and extent of suspected cancer in the lungs, while later tests are done to determine if the cancer has metastasized to other sites. A sample of sputum (coughed up mucus) may be examined for cancer cells, but the definitive diagnosis is made by taking a biopsy of lung tissue.
Treatment Team
The treatment team will most likely include a medical oncologist, radiation oncologist, thoracic surgeon, pulmonologist, oncology nurse, and social worker.
Clinical Staging, Treatments, and Prognosis
The staging, treatment, and prognosis for bronchoalveolar lung cancer is the same as for other NSCLS. The stage of the cancer is based on the TNM system. This considers the tumor size and how much it has grown (T), whether the cancer has spread to the lymph nodes (N) and whether it has metastasized (M) to distant sites in the body.
Stage Ia
T1 N0 M0. The tumor is no larger than 3 cm (about 1.2 in) with no sign of lymph node involvement or metastasis. Treatment at this stage is likely to involve only surgery to remove the tumor. Surgery can remove one lobe of the lung (lobectomy) or a part of a lobe (wedge resection or segmentectomy). The estimated five-year survival rate when NSCLC is treated at this stage is 75%, however lung cancer is rarely diagnosed this early.
Stage Ib
T2 NO MO. The tumor is larger than 3 cm, but cancer has not spread beyond the lung. Treatment is usually surgery. Sometimes radiation therapy is recommended following surgery. The estimated five-year survival rate when NSCLC is treated at this stage is 55%.
Stage II a
T1 N1 MO. The tumor is smaller than 3 cm, but cancer has spread locally to the lymph nodes, although it has not metastasized to distant sites. Treatment at this stage is usually surgery to remove a lobe of the lung or sometimes the entire lung. (Individuals can survive well with a single lung.) Radiation therapy may follow surgery. Supplemental chemotherapy at this stage is being studied in clinical trials. The estimated five-year survival rate when NSCLC is treated at this stage is 50%.
Stage II B
T2 N1 MO or T3 N0 M0. Either the individual's condition is the same as in stage IIA except that the tumor is larger than 3 cm, or the tumor has grown into the membrane surrounding the lungs, the chest cavity, diaphragm, or membrane surrounding the heart. Treatment is similar to stage IIA. The estimated five-year survival rate when NSCLC is treated at this stage is 40%.
Stage IIi a
T1-3 N2 MO or T3 N1 M0. The tumor can be any size, but cancer has spread to additional, more distant lymph nodes, but has not metastasized to distant sites. Alternately, the tumor is growing into the surrounding membranes or muscles, but only local lymph nodes are involved. Treatment at this stage depends on where in the lung the cancer is located. Most bronchoalveolar cancers are located on the edges of the lung. Surgery of the lung and lymph nodes may be performed depending on where the tumor is located, but chemotherapy and radiation therapy are also required. The estimated five-year survival rate when NSCLC is treated at this stage is 10–35% depending in part on whether the tumor is operable.
Stage IIi B
Any T4 or N3 and M0. The tumor has invaded nearby organs such as the esophagus, trachea, large blood vessels or heart or the cancer has spread to large and diverse lymph nodes, although it has not metastasized to distant organs. Surgery at this stage will not removed the cancer. Individuals in good health undergo chemotherapy and radiation therapy. The estimated five-year survival rate when NSCLC is treated at this stage is less than 5%.
Stage Iv
Any M1. Cancer has metastasized to distant organs. Stage IV cancer is almost incurable. The goal of treatment is to improve the quality of life or extend life. Aggressive chemotherapy may be used for individuals in otherwise good health. Alternately, care may be given to make the individual as comfortable as possible. The estimated five-year survival rate when NSCLC is treated at this stage is about 2%.
Alternative and Complementary Therapies
Although many alternative therapies are said to protect against developing cancer, few claim to cure lung cancer. At one time, large doses of vitamin A and beta-carotene found in yellow and dark green vegetables were promoted as decreasing the risk of lung cancer. However, according to the National Institutes of Health Office of Dietary Supplements, in a controlled, randomized study, researchers found that smokers taking vitamin A and beta -carotene supplements were 46% more likely to die of lung cancer than smokers who did not take these supplements.
Acupuncture has proved effective in many people to deal with the nausea associated with chemotherapy.
Unlike traditional pharmaceuticals, complementary and alternative therapies are not evaluated by the United States Food and Drug Administration (FDA) for either safety or effectiveness. Patients should be wary of "miracle cures" and tell their doctors if they are using herbal remedies, vitamin supplements or other unprescribed treatments. Alternative and experimental treatments normally are not covered by insurance.
Coping With Cancer Treatment
Lung cancer is often not diagnosed until it is too far advanced to be cured, The overall long-term survival rate for individuals with lung cancer is about 13%. In addition to coping with the psychological stress of cancer, individuals face many unpleasant side effects from treatment, such as nausea, vomiting, fever, and weakness. New drugs have improved the control of nausea and pain, but not eliminated the problem.
Hospitals and cancer centers provide social workers to help families cope with changes brought on by cancer ranging from finding a transportation to and from treatments to the financial stress of illness to preparing for impending death. Religious counseling and support is also available, as are support groups for those afflicted with specific cancers and their family members. Hospice care can help the individual maintain some control over their quality of life in the event of terminal cancer.
Clinical Trials
Because NSCLC is one of the more common cancers, many clinical trials are underway to determine the effectiveness of new drugs and new therapies. A list of clinical trials that are currently recruiting patients with bronchoalveolar lung cancer can be found by entering the search term "bronchoalveolar lung cancer" at the following web sites:
- National Cancer Institute
- National Institutes of Health Clinical Trials
- Center Watch: A Clinical Trials Listing
Some of these trials involve experimental medications, while others involve various combinations of chemotherapy and radiation therapy.
Prevention
Avoiding smoking is the best way to prevent all lung cancers. Between 85% and 90% of people who develop lung cancer are smokers. No matter how long or how much an individuals has smoked, the chance of getting lung cancer decreases and general health improves by quitting smoking.
Other ways to prevent all lung cancers include avoiding breathing gasoline and diesel fuel fumes and exposure to asbestos and other airborne chemicals known to be carcinogens. Maintaining a healthy weight, exercising regularly, and eating a diet high in vegetables and fruits are other positive steps individuals can take. Some nutritionist advise including 5–10 cups of green tea daily in the diet because of green tea's antioxidant properties. However, all these diet and exercise precautions are of minor importance when compared to the preventative effects of not smoking.
Questions to Ask Your Doctor
- What type of lung cancer do I have?
- What stage is my cancer?
- Why do you recommend this particular treatment and what are the alternatives?
- What kind of side effects can I expect from treatment?
- Are there any clinical trials that might be appropriate for me?
Special Concerns
Individuals with lung cancer often show no symptoms until their cancer is far advanced. Studies have found that regular chest x rays or CT scans of smokers' lungs do not increase the rate of early detection.
Resources
Periodicals
Dumont, Pascal, et al. "Bronchoalveolar carcinoma: Histopathologic Study of Evolution in a Series of 105 Surgically Treated Patients" Chest 113, no.2 (February 1998):391-396.
Rachita, Mircea et al. "Bronchoalveolar Carcinoma in a 58-Year-Old Man," Consultant. 43, no. 3 (March 2003): 357-360.
Organizations
American CancerSociety. 1599 Clifton Road NE, Atlanta GA 30329-4251. 1-800-ACS-2345.
National Cancer Institute Information Line 1-800-4-CANCER (1-800-422-6237)
Other
American Cancer Society. Lung Cancer, 12 November 2004 [cited 6 March 2005].
Maghfoor, Irfan and Michael Perry. Lung Cancer, non-Small Cell, 10 January 2005 [4 March 2005].
—Tish Davidson, A.M.
