Incidence and Risk Factors
In the United States, lung cancer is the leading cause of cancer death in men, and it surpassed breast cancer as the leading cause of cancer death in women in the latter part of the 1980s.
It has been estimated that 80% of lung cancer deaths among men (approximately 65,000 deaths per year) and 75% of lung cancer deaths among women (approximately 27,000 deaths per year) are attributable to smoking. It was also calculated that a 35-year-old man who smokes 25 or more cigarettes per day has a 13% risk of dying of lung cancer before the age of 75 years, a 10% chance of dying of coronary heart disease, and a 28% chance of dying of smoking-related disease.
Increases in lung cancer risk accompany exposure to carcinogens, such as asbestos, radon, bis (chloromethyl) ether, polycyclic aromatic hydrocarbons, chromium, nickel, and inorganic arsenic compounds. The association with occupational exposure to these agents appears to be independent of cigarette smoking.
Types of Lung Cancer
Non-small cell lung cancer is the most common type of lung cancer. It usually spreads to different parts of the body more slowly than small cell lung cancer.
Lung cancer is divided into non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). The non-small-cell composes the majority of the lung cancers and is subdivided into several types based on the pathology and they are treated in the same fashion. Treatment depends on the stage of the cancer.
Images on the right show how the cell types look under microscope, which requires interpretation by a pathologist.
Lung Cancer Stages
Lung cancer almost always begins in one lung and, if left untreated, can spread to lymph nodes or other tissues in the chest (including the other lung). Lung cancer can also spread throughout the body, to the bones, brain, liver, or other organs. As in most cancers, there are four stages, representing a continuum, with stage I generally being a tumor confined to the lung only and no sign of spread to the lymph nodes or outside the lungs, to stage IV, which implies tumor that has spread beyond the lung, possibly even distant organs.
During the last decade, an exciting new modality, whole-body positron emission test (PET), came into use to help stage lung cancer, in addition to standard CT scans. It is a form of nuclear study that includes an injection of radioactive substance into the body where it is concentrated in cancerous sites, which are then more readily detectable. It appears to be very valuable in diagnosing and staging lung cancer In addition, it appears useful in differentiating benign from malignant lesions when investigating a solitary pulmonary nodule.
Image on left shows a rotating image of PET scan in a patient with a lung tumor, left side, shown as large, black density.
Treatment Options for Lung Cancer
For early stage (I, II), operable cancers in healthy patients, surgical removal is normally accepted as the treatment of choice, with reported cure rates as high as 70% or more (1, 2). If a patient has an early stage cancer, but their ability to withstand surgery is in question because of coexisting medical problems (a condition generally referred to as “medically inoperable”), they may be offered Radiation Therapy instead of surgery. Extended disease-free survival is also observed with Radiation Therapy, though the reported rates tend to be lower compared with surgical results. Learn more about: Radiation Therapy for Lung Cancer.
Stereotactic radiosurgery with the CyberKnife System, sometimes also referred to as stereotactic radiotherapy, is a new technique that shows great promise in the treatment of early stage lung cancer, in patients who may not be healthy enough to withstand the customary curative surgical procedure. Learn more about: CyberKnife for Lung Cancer.