The bronchus describes the tubes which direct air into and out of the rest of the lungs. Because cells in the bronchus have exposure to airborne toxins, many cases of lung cancer begin in the tissue of the bronchus. Carcinomas of the bronchus can be of different varieties and can cause different symptoms depending on how far they have spread.
Types
Most cases of lung cancer, the American Cancer Society explains, begin in the bronchus. Most cases of lung cancer are divided into small cell and non-small cell types. The most common type of lung cancer is called non-small cell lung cancer; one subtype of this kind of cancer that commonly affects the bronchus is called squamous cell carcinoma. Small cell lung cancer usually begins in the bronchus and makes up between 10 and 15 percent of all cases of lung cancer.
Symptoms
Approximately 25 percent of all cases of lung cancers, the Merck Manual explains, are asymptomatic and are normally diagnosed due to chest imaging for other reasons. A localized tumor that has not spread into other tissues can cause a cough and trouble breathing. If the tumor spreads regionally, it can cause chest pain and hoarseness if it pinches the laryngeal nerve. Carcinomas of the bronchus that metastasize to other organs can cause dysfunction of those organs; common sites of metastasis include the liver, brain and bone.
Risk Factors
The most important risk factor for the development of carcinomas in the bronchus is cigarette smoking. The age of the patient, the length of time that the patient smoked and how much the patient smoked per day all factor into the patient's risk of developing carcinoma of the bronchus. The Merck Manual does note, however, that 15 percent of all cases of lung cancer occur in patients who have never smoked. Exposure to asbestos, radon, radiation, nickel and other environmental toxins may be behind these cases.
Diagnosis
Chest imaging such as X-rays or CT scans can be used to detect tumors of the bronchus, the Mayo Clinic explains. Patients with a persistent cough can also have their sputum analyzed for the presence of abnormal bronchus cells. Growths or tumors of the bronchus typically require a biopsy of the tissue in order to definitively make a diagnosis of carcinoma of the bronchus. Whole body MRI and CT scans can then be used to determine how far the cancer has spread, which can shape treatment.
Treatment
Patients with carcinoma of the bronchus have a variety of treatment options, the Mayo Clinic notes. Surgical treatment, which either removes all or part of the lung is a common initial mode of treatment. Many patients also benefit from radiation, which uses high energy X-ray beams to damage and kill the cancerous cells. Chemotherapy utilizes chemicals which are toxic to rapidly dividing cancer cells. Bevacizumab, MayoClinic.com explains, is a drug which prevents carcinomas of the bronchus from making new blood vessels. Another biological drug, called erlotinib, blocks a signal that cancer cells need to divide.
