Factors Contributed to the Development of Cancer - Essay Example

Causes of Cancer Causes of Cancer Cancer is the second most common cause of death, killing 318 in every 100,000 Americans. It is predicted that over 1,500,000 new patients will be diagnosed with cancer and nearly 600,000 will die because of it in 2015 (American Cancer Society, 2015). Cancer occurs when cells undergo uncontrollable growth. Depending on the tissue and organs that are affected, doctors and scientists distinguish nearly 100 types of the disease. Despite numerous efforts to find the cure or develop the vaccine, cancer, for the most part, remains an untreatable illness. Direct causes are unknown. However, scientists have identified particular factors that are likely to contribute to the development of the disease. The most notable among them include exposure to cancerogenic chemicals, genetic factors, and radiation. Specific substances are believed to cause certain types of cancer. Such chemicals are called carcinogens. Usually, they cause mutations in the genes and trigger neoplastic processes. Tobacco smokers with lung cancer and miners with mesothelioma are classic illustrations of substance-associated type of disease. 87% of lung cancer patients are smokers. Tobacco smoke contains nitrosamines, polycyclic aromatic hydrocarbons, and dozens of other carcinogenic substances. Over 30% of total cancer deaths across the U.S. and nearly 20% of the cases worldwide are attributed to tobacco (American Cancer Society, 2015; National Cancer Institute, 2015). Profound studies have also revealed the link between smoking and cancer of the larynx, kidney, stomach, pancreas, esophagus, as well as myeloid leukemia. Lung cancer rates in the Western World traditionally reflect current smoking patterns. Hence, the decline in popularity of smoking in the 1950’s was accompanied by the decreased lung cancer occurrence in the 1990s, while death rates surge dramatically after the increases in smoking. Nevertheless, the number of smokers across the globe is rising continually and already exceeds one billion. Occupation-related cancer comprises 5 to 20% of the cases. The minimum of 200,000 people worldwide die annually from cancer induced by harmful workplace conditions. The majority of deaths linked to occupational risk factors happen in the developed countries. In the U.S. only, 20,000 cancer deaths and 40,000 newly registered cases a year can be attributed to dangerous chemicals inhaled or contacted with while at work (American Cancer Society, 2015). For instance, miners inhaling asbestos fibers are at risk of getting lung cancer or mesothelioma. Exposure to benzene at oil refineries, shoe factories, and rubber plants may cause leukemia. Genetic factors can also play a crucial role in cancer development. Mutations of the genome alter the growth patterns and make targeted cells potentially cancerous. Sometimes, genetic mutations may be present from the moment of birth, and a syndrome is called family cancer syndrome. The mutation usually occurs in one or several tumor suppressor genes. Such individuals are predisposed to having cancer, but they do not necessarily develop clinical signs. Every gene is represented in the cell with two copies called alleles. Cancer syndromes are usually transferred in the autosomal dominant way. This means that even one altered allele is enough for the individual to be predisposed to cancer. Potential children of such a person and an individual with two intact alleles are at a 50% risk of being born sick (Brown & Anderson, 2007).  The regularity, called a two-hit hypothesis, says that the first hit is the genome mutation and the second one happens later in life. Since only one allele is to be altered, the chance of developing a disease is higher in affected people than in the rest of population. Cancer syndromes are frequently associated with an increased lifetime risk of producing cancer as well as with the development of numerous independent primary tumors. Classic examples of inherited family cancer syndromes include Lynch syndrome and breast-ovarian cancer syndrome. Some other known diseases are Fanconi anaemia, Li-Fraumeni syndrome, and familial adenomatous polyposis. Nearly 10% of neoplastic transformations are the result of exposure to radiation (Little, 2000). Large portion of information was acquired in clinical studies held on the Japanese atomic explosion survivors. The mechanism of such processes is well studied, though quantitative methods of suggesting the risk levels are still underdeveloped and cannot be fully applied. Major damage usually kills the cell or makes it unable to reproduce. The effect results in the acute radiation syndrome, but such heavily damaged cells do not become cancerous. On the contrary, moderate damage may leave a partially functional cell that would proliferate and finally develop into cancer. The researchers suggest that mutations do not normally occur immediately after exposure to radiation. Cells that survive are likely to have obtained a genomic instability. Therefore, future generations are at an increased risk of having mutations. The affected cell undergoes multiple stages of transformation that may develop into a tumor later in life. The neoplastic processes can be subdivided into three major interdependent stages: physical changes of the cell, the loss of life-limiting cell regulation, and pre-tumor alterations. Radiation-induced cancer is not limited to certain organs, age, or sex. It can also affect animals. Usually, it takes 10-15 years for solid tumors to develop, but sometimes the symptoms may manifest even in 40 years after exposure. For leukemias the period is typically 2 to 8 years (Little, 2000). Some individuals, especially those suffering from retinoblastoma or Gorlin syndrome, are more susceptible to developing radiation-induced cancer than the general population. Children and teenagers are twice more likely to develop leukemia than adults. Radiation exposure prior to delivery is associated with an effect ten times stronger. Cancer can be triggered by numerous factors. Most commonly, the neoplastic process is preceded by a mutation in the genome. As of today, researchers have revealed the strong link between cancer occurrence and such factors as smoking, radiation, hereditary predisposition, and exposure to certain industrial chemicals. Studies aimed to explore the nature of cancer have been conducted over decades and have involved solid investment and human resources. Advancement in medicine and technology has given the opportunity to approach the nature of the disease. A lot has been unveiled, but the most important discoveries are yet to be made. References American Cancer Society. (2015). Cancer Facts and Statistics. Retrieved from http://www.cancer.org/research/cancerfactsstatistics/ Braun, C. & Anderson, C. (2007). Pathophysiology: Functional alterations in human health. Philadelphia: Lippincott Williams & Wilkins Little, J.B. (2000). Ionizing radiation. Hamilton. National Cancer Institute. (2015). Cancer Statistics. Retrieved from http://www.cancer.gov/statistics Read More