It may be surprising to hear that lung cancer causes more total deaths than any other type of cancer, in both men and women. Lung cancer is also high on the list of the most common cancers: Every year in the United States, nearly a quarter of a million new cases of lung cancer are diagnosed. Lung cancer is extremely rare in people under the age of 45, with less than 3 percent of the lung cancer cases occurring in this age group. In contrast, about seventy percent of lung cancer cases are in individuals over the age of 65.
The vast majority of lung cancer cases are due to smoking tobacco. In fact, over ninety percent of lung cancer cases are caused by smoking tobacco. In the early 20th century, cigarette smoking was much less common, and lung cancer was rare. After heavy marketing of cigarettes started, the number of cases of lung cancer increased dramatically. As smoking becomes less common due to education about the health dangers of smoking and people being urged to quit smoking, the prevalence of lung cancer cases is projected to drop over time.
Other potential causes of lung cancer, besides cigarette and other tobacco product smoking, include exposure to asbestos, genetic susceptibility, exposure to certain toxic chemicals, arsenic poisoning, extremely poor air quality, exposure to radon gas and radiation. Lung cancer is likely when a person inhales certain toxic chemicals, such as gasoline fumes, mustard gas or coal dust, especially over a long period of time. Many of these chemicals are present in certain professions, and workplace safety precautions are taken to prevent inhalation of cancer-causing chemicals. Asbestos is a substance, actually a mineral, that was used in construction for the desirable qualities that it had for builders, such as sound resistance and fireproof insulation. Unfortunately, it was discovered that if the insulation fibers were inhaled, they could cause a variety of serious diseases, including lung cancer and mesothelioma: another type of cancer that commonly affects the pleura, the membranes that cover the lungs.
There are several types of lung cancer. In some cases, lung cancer called secondary lung cancer can occur when another type of cancer spreads to the lungs. These cancers are not composed of cancerous lung cells, but cancer cells from other tissues of the body. Primary lung cancer, or cancer that develops from lung cells, comes in two major varieties, called small cell lung cancer and non-small cell lung cancer. Small cell lung cancer is the more aggressive of the two types of lung cancer. It is also less common than non-small cell lung cancer, affecting less than twenty percent of lung cancer patients. Small-cell lung cancer is named because the cancer cells themselves are small, but they divide so rapidly that metastasis (spreading) and large tumors are common. Small cell lung cancers come in two types: small cell carcinomas and combined small cell carcinomas. Non-small cell lung cancers spread less quickly and generally have higher survival rates. Non-small cell lung cancers can be adenocarcinomas, which usually occur in the outer lung, squamous cell carcinomas, which are more common in the center of the lung near the airways, or large cell carcinomas, which can appear anywhere in the lung. Of the three types, large cell carcinomas are the most aggressive and rapidly-growing, but they are still not as aggressive as small cell lung cancers.
Like all cancers, lung cancers are staged based on whether or not they have spread to other parts of the body. Lung cancers caught in the early stages of development have a higher cure rate. Lung cancer is also usually asymptomatic in the early stages, so it is more likely that lung cancer will be caught later during the course of the disease. Prognosis varies widely from case to case, but a person with non-small cell lung cancer generally has a better prognosis than someone with small cell lung cancer. Even people with end-stage (stage IV) lung cancer can benefit from chemotherapy treatments; the treatments are unlikely to make the cancer go away at this point, but they can improve quality of life for the patient.
When lung cancer symptoms do occur, they may include chest pain, a lingering cough, weight loss, coughing up blood, severe fatigue and wheezing. Late stage lung cancer may have additional symptoms, like joint pain, muscle weakness, bone pain, difficulty swallowing, swelling of the arms or face, voice changes and facial paralysis. Additional symptoms, such as nausea, anemia, hair loss, appetite problems and diarrhea or constipation may occur as a side effect of chemotherapy treatments.
Lung cancer may be discovered when a person gets a chest CT scan or X-ray for another medical condition. In some cases, lung cancer may be suspected in individuals who are symptomatic and have a history of smoking. A combination of medical imaging, laboratory tests and lung biopsies are used to diagnose and stage lung cancer.