If a tumor remains in one place and shows limited growth, it is commonly considered to be benign. “Cancer that originates from lung cells is called primary lung cancer. Primary lung cancer can start in the airways that branch off the trachea to supply the lungs (the bronchi) or in the small air sacs of the lung (the alveoli)” (Hong, Tsao 2008). Instead, if cancer originated elsewhere and metastasized to the lungs, it is called “secondary”. These two types of cancer are taken as different forms of cancer from diagnostic and treatment perspectives
Lung cancer is generally classified into two main types based on the outlook of cancer under a microscope: Non- small cell lung cancer and small cell lung cancer. Non – small cell lung cancer is the type found in the majority of cases diagnosed, whereas small cell lung cancer with lesser cases. “Since lung cancer tends to spread or metastasize very early after it forms, it is a very life-threatening cancer and one of the most difficult cancers to treat”(Stoppler).
The main cause of lung cancer can be related to smoking and inhaling carcinogens in tobacco smoke. “Air pollution, particularly smoke from fossils, appears to increase the risk of lung cancer but its effect is small compared with that of cigarette smoking”(Williams 20). Several studies have shown that lifetime exposure to smoking can lead to the development of lung cancer. The reason for smoking being harmful is that tobacco contains an exorbitant amount of chemical agents, including carcinogens which cause cancer.
The studies have also shown that radon is the primary cause of lung cancer among non – smokers. Overall it can be said that radon is the second leading cause of lung cancer. Radon is tasteless, odorless and invisible gas produced by the decay of naturally occurring uranium water and soil. . .“Although the progeny of radon is now a well- recognized cause of lung cancer, radon itself has again become a topic of controversy and public health concern because it has been found to be a ubiquitous indoor air pollutant to which all persons are exposed”(Health Effects 22) . .