Richard Koehler, MD
Virginia Mason Medical Center (Seattle, WA)

Cancer is a disease process where the normally regulated process of cells growing, dividing and dying becomes uncontrolled. Cancer results from these alterations, and can result in the rapid growth of cells which can develop into mass, sometimes called a tumor. The cancer cells can invade surrounding structures or organs, or break off from the main mass and travel into the lymph system or blood systems. If these cancer cells invade the blood system or lymph system, they can form a new growth in other parts of the body, resulting in metastasis, or growths of cancer in bone, brain or other tissues.

Lung cancer is a deadly cancer and is commonly associated with cigarette smoking. Although it historically affected more men, sadly as smoking rates in women have increased,cancer rates are now nearly equal. The American Cancer Society estimates that 98,620 women will be diagnosed with lung cancer this year alone, of which 70,880 are estimated to die from lung cancer. Although there is more publicity and education about breast cancer, lung cancer kills more women each year than breast cancer, colon cancer and uterine cancer combined. Overall, these statistics are concerning given that breast cancer affects nearly twice as many women than does lung cancer but will kill only half as many women.

The lungs are a set of paired organs found in the chest cavity and are connected directly to the heart in terms of its blood supply. The air passages that go to the lungs begin with the trachea at the back of the throat, which divides into a right and left main bronchus and then divides again into a number of smaller airway branches known as bronchi. The lungs are anatomically divided into lobes: there are two lobes on the left and three lobes on the right. The area between the right and left lungs is known as the mediastinum and contains the trachea, heart, esophagus, or food tube, and lymph nodes.

There are many different cell types in the lung, and cancer can develop out of any of these different cells, but the vast majority of lung cancers arise from the bronchi, or respiratory tree. The majority of lung cancers are either non-small cell lung cancer, which account for roughly 85-90% of lung cancers, or small cell lung cancer which accounts for 10-15%. As these different types of lung cancer require different treatment, it is important to establish a clear pathologic diagnosis.

Small cell lung cancers tend to be caused by smoking, as it is rare to diagnose it in a non-smoker. These cancers tend to grow rapidly and spread to other parts of the body, and therefore are most often treated with systemic treatments like chemotherapy and radiation therapy. Surgery is most often used to help establish a diagnosis and in rare situations can be used to treat very early small cell cancers in the lung.

Non-small cell lung cancers are subdivided into squamous cell, adenocarcinoma or large-cell undifferentiated cancers. In general, non-small cell cancers tend to be slower growing.  The squamous cell tumors tend to be centrally located while adenocarcinoma tumors tend to be peripherally located. More than 80% of these cancers are caused by cigarette smoking or exposure. Early stage non-small cell cancers can sometimes be treated with surgery alone, while later stage cancer might require a combination of surgery, chemotherapy, and radiation therapy.

Once the diagnosis of lung cancer has been established, it is important to get an idea of its stage, which is based upon how big the cancer is, and if it has spread outside of the lung to lymph nodes or other parts of the body. Staging is initially based upon clinical information and radiology imaging, but will often require a tissue diagnosis to confirm results prior to initiating treatment.

Because smoking and second hand smoke are risk factors in the development of lung cancer, stopping smoking is the single best way to minimize your risk of developing lung cancer. Screening for lung cancer in asymptomatic, and high risk patients remains controversial and currently is not recommended. Routine physical examinations with a primary care provider is recommended. Notifying your doctor if you develop potential symptoms of lung cancer, such as coughing up blood, changes in voice, unexplained weight loss, chest pain, or bone pain offers the best chance of finding and treating lung cancer.

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