What is bronchoalveolar lung cancer?

Related conditions:
Pleural effusion, pneumonia

Definition:

Bronchoalveolar lung cancer is a type of NSCLC that arises in the alveoli (air sacs of the lung). It can begin as either a single site or multiple sites, or spread rapidly as a pneumonic form. Bronchoalveolar lung cancer is less likely than other types of NSCLC to spread beyond the lungs.

Risk factors: The most common cause of lung cancer is smoking cigarettes. Another major cause is exposure to secondhand smoke. Other risk factors include exposure to radon gas or asbestos, environmental pollution, tuberculosis, lung disease, and an inherited predisposition to lung cancer.

Etiology and the disease process: With bronchoalveolar lung cancer, cells in the alveoli begin to grow wildly. As they grow, they progress along the alveolar walls. Multiple sites may develop and then converge to consolidate some areas of the lungs. An obstructed area of the lung may become pneumonic.

Incidence: NSCLCs account for about 75 percent of all lung cancers. Bronchoalveolar lung cancer makes up about 2 to 3 percent of this group. Although 10 percent of patients with lung cancer in the United States are nonsmokers, 25 to 30 percent of patients with bronchoalveolar lung cancer are nonsmokers. It is more common in women.

Symptoms: The symptoms of bronchoalveolar cancer are coughing, shortness of breath, wheezing, chest pain, large amounts of watery sputum, and hemoptysis (coughing up blood). On physical examination, the lungs are dull to percussion (tapping on the chest wall), and breath sounds may be weak or absent on auscultation (listening with a stethoscope). If the tumor is pressing on a nerve, it can cause shoulder pain or hoarseness.

Screening and diagnosis: Currently, there is no accurate, inexpensive screening test for bronchoalveolar lung cancer. Researchers are working to develop such a test by looking at a marker in the blood and also at breath analysis.

To diagnose lung cancer, pulmonary function tests and a chest X ray may be performed. Chest X rays can demonstrate most lung cancers, except the very small. More sensitive tests are computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET) scans.

To differentiate between the types of lung cancer, a biopsy of the tumor must be performed. Bronchoscopy, thoracoscopy, or mediastinoscopy may be performed to examine pulmonary secretions and the lymph nodes of the lung. If the cancer exists on the periphery of the lung, it may be necessary to perform a needle biopsy through the chest wall. If none of these procedures is effective in determining the type of lung cancer, a surgical procedure called a thoracotomy (opening the chest) can be performed.

The actual diagnosis of bronchoalveolar lung cancer is made by the pathologist, who examines the tumor cells under a microscope. The pathologist identifies the type of lung cancer and stages the cancer. All NSCLCs are staged in the same way, using a combination of numeric tumor grading and the TNM (tumor/lymph node/metastasis) stages. The stages are as follows:

• Stage IA, T1 N0 M0: The tumor is less than 3 centimeters (cm) and there is no lymph node involvement or metastases.





• Stage IB, T2 N0 M0: The tumor is greater than 3 cm, but it has not spread beyond the lung.





• Stage IIA, T1 N1 M0: The tumor is less than 3 cm, and there is spread to local lymph nodes.





• Stage IIB, T2 N1 M0, or T3 N0 M0: Either the tumor is greater than 3 cm, or it has spread into the outside of the lungs, the chest cavity, or the pericardium (sac around the heart).





• Stage IIIA, T 1-3 N2 M0, or T3 N1 M0: Either the cancer has spread to distant lymph nodes but has not metastasized, or the cancer has spread into adjacent tissues and muscles and has spread to local lymph nodes.





• Stage IIIB, T4 N3 M0: Either the cancer has spread to nearby organs or it has spread to distant lymph nodes but has not metastasized.





• Stage IV, M1: The cancer has metastasized to distant organs.

Treatment and therapy: Treatment of lung cancer can include surgery, chemotherapy, and radiation. To remove a bronchoalveolar tumor, the surgeon can perform a wedge resection, a lobectomy, or a pneumonectomy. Chemotherapy for lung cancers is effective only 35 percent of the time. The most commonly used drugs are combinations of cisplatin (Platinol), carboplatin (Paraplatin), vinorelbine (Navelbine), vincristine (Oncovin), vinblastine (Velban), paclitaxel (Taxol), docetaxel (Taxotere), and gemcitabine (Gemzar). Newer chemotherapy drugs that interfere with cell growth and reproduction as well as angiogenesis (formation of new blood vessels) are being used. They are gefitinib (Iressa), erlotinib (Tarceva), and bevacizumab (Avastin).

Radiation therapy for bronchoalveolar lung cancer is not effective as a cure, so it is reserved for treatment when surgery is not possible.

Prognosis, prevention, and outcomes: Patients with lower stage cancers survive longer than those with high-stage cancers. Research has shown that patients who have never smoked respond better to treatments for bronchoalveolar cancer. The best way to avoid lung cancer is by not smoking and by avoiding exposure to secondhand smoke.

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