Cancer is one of the most common causes of death worldwide. Every year, various types of cancer kill millions of people. The problem of cancer disease is unique because of its complexity and importance to humankind. Cancers affect all segments of the population, causing enormous damage to society. Although malignant tumors are extremely diverse and complex for the perception, the risk factors and mechanisms of development of cancer are well known enough so that it becomes possible not only to heal, but also to engage in cancer prevention. Cancer is the most difficult and dangerous disease, since it can take many forms and start in all organs of a human body. The causes of this disease are very diverse; however, they are primarily associated with individual characteristics of a human body, but nonetheless, many investigators believe that cancers are associated with the environmental exposure (Moore, 2007, p. 136).
Definition of Cancer Diseases
According to Moore (2007), cancer is a "generic term" for a large group of diseases that can affect any part of a body (p. 136). This notion implies the use of the terms such as malignant tumors and neoplasms. The rapid creation of abnormal cells, which "grow beyond their usual boundaries, invade adjoining parts of a body, and spread to other organs", is a characteristic feature of any cancer (Pierce & Jameton, 2003, p. 52). Basically, cancers originate from a particular cell or a group of cells that begins to multiply and grows randomly displacing normal cells. Cancer can take the form of leukemia that evolves in the bone marrow in a form of the white blood cells or solid tumors found in any part of the body (Moore, 2007, p. 167). This process is called metastasis. Metastases are the major cause of death from cancer.
Cancer arises from one single cell: the transformation of a normal cell into a tumor cell is a multistage process, typically a progression from "lesions into malignant tumors" (Moore, 2007, p. 174). These changes occur because of the interaction between the genetic factors and the three categories of human external factors, including physical, chemical, and biological carcinogens. Cancerous tissue is a movable and changeable mass. Its behavior depends on many factors such as the intensity of protective anti-reactions in a particular case. Human immune system can destroy a tumor partially or completely. It can also block the cancer cells at an early stage and not allow them to penetrate deep into body. Nevertheless, the fact why children get cancer is poorly studied. Cancer in children is still the most inexplicable disease, and there is no reason to believe that it can be prevented. Violation of fetal development, impact of adverse environmental factors, and parents' professional hazards (i.e. "ionising radiation (radon, radiation-exposed workers) and ultraviolet radiation in outdoor workers") are the main factors contributing to the development of malignant tumors in children (Espina et al., 2015, p. 85).
Causations of Cancer
Basically, cancer is caused by the metabolic processes in cells and derestriction of intracellular processes by organism; moreover, it is "a definite pathological process" (Moore, 2007, p. 136). Young dividing cells lose their ability to "differentiate" because of the acquisition of new skills and the partial independence of the regulatory systems of a body: i.e., they do not get the proper function and do not form the normal operating tissues (Pierce & Jameton, 2003, p. 18). These cells become useless as they do not participate in the life of an organism. Hence, a body tries to get rid of them with the help of immune responses, which are not always effective. The excess of the young, breeding, and not working cells requires an increasing amount of energy and food resources, which leads to the fact that these cells attack a tissue or an organ (Moore, 2007, p. 140). These cells, which can be called cancerous, invade body tissues, infiltrate, and destroy them, capture the blood and lymph vessels, and distribute throughout the body – i.e. they "metastasize" or "continue to multiply intracellularly" (Moore, 2007, p. 293). According to Moore (2007), malignant tumors grow into the surrounding tissue and destroy them, while tumor cells get into the bloodstream or lymphatic system, spread through the body, and settle in various organs and tissues to form metastases; benign tumors do not metastasize but may pose a danger because of their localization (p. 141).
Therefore, a presence or an absence of metastases, as well as the scope and rate of metastasis, depends on the immunobiological state of an organism. The appearance of a tumor begins with the appearance of a small group of cells with a tendency to the unlimited division in a tissue. The stages that precede malignancy are called "pre-malignant conditions" (Moore, 2007, p. 141). Each cancer has its pre-malignant condition; this is confirmed by many clinic observations and experiments on animals (Colao, Muscogiuri, & Piscitelli, 2016, p. 3). The stages of development of tumor and the possibility of further strengthening of its malignancy are reflected in the concept of tumor progression. During the progression, the independence of tumor from the body's systems increases. Hence, one can conclude the following: metabolic processes in cells and weakening of control over the processes by intracellular organism can cause a tumor.
The reasons for the appearance of tumor have not been investigated completely. An organ's predisposition to cancer is inherited, i.e. it is a "genetic predisposition" (Moore, 2007, p. 159). In other words, hormonal abnormalities in structural body or local disturbances in any organ are inherited. These abnormalities can lead to cancer development. However, the presence of tissues is not enough for the occurrence of cancer or carcinogenesis. "Mutagenic markers" that cause changes in the genetic apparatus of the cell and tumor transformation are essential in this case (Colao, Muscogiuri, & Piscitelli, 2016, p. 3). Such incentives may be internal or external – i.e., physical, chemical, viral, etc. For example, the internal incentives are in charge of the increased production of hormones or other products of metabolism and imbalances, while ionizing or ultraviolet radiation are the examples of the external incentives, i.e. physical incentives. These factors have mutagenic and thus "carcinogenic" impact, which brings into operation the mechanism that produces the cancer cells in increasing numbers (Moore, 2007, p. 160). It is believed that any cell has a "tumor program". This program is recorded in specific genes – "oncogenes" (Moore, 2007, p. 558). Under normal circumstances, oncogenes are rigidly locked, but block can be removed, and thus, oncogenes have the opportunity to work under the influence of mutagens. Most oncologists state that a variety of environmental factors that affect body, not excluding the chemical and viral effects, can be the cause of cancer (Moore, 2007, pp. 134-135). However, whatever the impact is, it is longstanding: cancer does not occur suddenly, it is preceded by the development of a number of pathological processes, which can cause the malignant tumors. It follows that there are two basic theories of cancer - a chemical theory and a viral theory.
Environmental Influence on Cancer Diseases
Human habitat – i.e. environment – is characterized by a combination of physical, chemical, and biological factors that can have a direct or indirect, immediate or remote effect on the activity and health of a person under certain conditions. According to Moore (2007), the steady growth of toxic substances into the environment primarily affects the human health and worsens the quality of "agricultural products, water, and oxygen" (p. 174). The impact of the highly pervasive "hydrocarbons produces a great risk of such diseases as cancer" (Pierce & Jameton, 2003, p. 46). The damage to the structure of DNA is the exciting cause of cancer, the result of which usually becomes an oncogene activation and the emergence of cancer cells, which is divided into uncontrolled systems of body. However, there is a need to have an effect on a healthy cell in order to cause the damage in its DNA. These various effects are called "risk factors" (Espina et al., 2015, p. 90). Risk factors are the causes that can increase the risk of cancer in humans. Previously, most of the causes of cancer have been associated with the environment or genetic predisposition to cancer. Nevertheless, the factors related to bad human habits, such as "smoking, alcohol and drug abuse, excessive use of poor-quality food and a sedentary lifestyle", have been added to this list (Moore, 2007, p. 135). "Aggressiveness" of the environment is a result of human activity and interaction with the different technologies. One of the main problems of the influence of the environment on the occurrence of cancer is a problem of water pollution with the various toxins. For instance, tap water contamination with different organic, organochlorine compounds, and heavy metals can lead to the disastrous consequences. Given that water is a basic component of a human body, any change of its structure caused by pollution and thereby change of its biological function may be the cause of a "cancer cell transformation" (Moore, 2007, pp. 361-362). The composition of automotive emissions includes over 200 chemicals, and oxygen is the key substance that provides human with the vital functions along with the water. For example, "an increased occurrence of lung cancer has been attributed to air pollution even in areas below the EU limits for daily air pollution" (Espina et al., 2015, p. 84). Air pollution disturbs the quality of gas exchange in the bodies, destroying the components of blood, leading to atrophy of organs and violation of their functions. It results in a hard metabolism and a decrease of energy production in the cells and "adaptive ability" of an organism (Espina et al., 2015, p. 84). It can be seen that small concentrations of contaminants adjust and change the cells' program information that often leads to cancer cell mutation. Many researchers believe that "cancer is caused by environmental factors in 60-90%" and this is confirmed by many studies (Espina et al., 2015, p. 85). This conclusion is based both on the epidemiological data showing a connection example between the intensity of smoking and lung cancer, or between the amount of fat in the diet, on the one hand, and the incidence of colon cancer on the other. In addition, epidemiological analysis reveals significant differences in the number of countries in the incidence of many types of cancer, and these differences are determined by the way of life, the type of food, and the intensity of the impact of toxic substances on humans (Espina et al., 2015, p. 88).
Every adult continually makes from 16 to 19 breaths per minute 24 hours a day. Hence, if carcinogen gets into the air, it automatically provides the "permanent negative effects" on humans (Espina et al., 2015, p. 86). It is proved that exposure of the small doses over a long time is more dangerous than a single contact with a significant number of carcinogen. Several tens or even hundreds of chemical compounds can affect a person in the industrial area simultaneously, and the effects of combining them are poorly understood. During the day, up to 20 000 liters of air pass through lungs, and even the lowest concentration of a carcinogen at a distance is dangerous. Harmful substances enter directly into the internal environment of a body – it is promoted by thin walls of alveoli and capillaries (Moore, 2007, p .177). A person cannot escape from these harmful substances – one can eat organic food and drink only pure water, but the toxins enter a human body through the air. Today, modern human spends time in areas where he/she is subjected to the additional cancer risk factors. There are the additional conditions for the accumulation of carcinogens since the air can circulate freely.
Symptoms, Treatment, and Prevention
The symptoms of cancer appear relatively late, when a tumor reaches a considerable size and disrupts the functions of body organs in which it grows. If an organ is hollow, its continuity may disrupt, there may also be "bleeding and abnormal discharges" (Pierce & Jameton, 2003, p. 20). A patient "feels weak, loses weight", his/her body temperature rises, he/she experiences pain (Moore, 2007, p. 135). A cure for cancer is the most complicated problem of the modern medicine. Today, one can say that the early detection of cancer is the "cure for cancer" during the first two stages of this disease. Currently, there are several major ways to treat cancer. Chemotherapy is one of the most effective and common treatment, as it "will permit the rapid onset of overwhelming infections or possibly cancer" (Moore, 2007, p. 184). This type of treatment involves receiving special medication in the form of injections and pills. They are taken to kill the "bad" cancer cells and cause them to stop uncontrolled increase. Chemotherapy is based on a technology that does not allow distinguishing the cells from each other so that patient's healthy tissues are exposed to the chemical attack too, which leads to the appearance of the severe side effects. Therefore, the effects on the immune system are inevitable for the increase of body's defenses. Various treatments are often used in conjunction with one another depending on the stage of disease and other factors. For instance, radiation therapy uses "high-powered X-rays" to kill cancer cells (Pierce & Jameton, 2003, p. 17). It is often used before surgery to reduce a tumor. A decrease of tumor reduces level of danger during the operation. Surgery is another effective form of treatment for cancer. Sometimes surgery is needed to remove a massive tumor, depending on where it is found. According to Espina et al. (2015), in developed countries, the majority of children recover from cancer disease after the surgical intervention (p. 84). Firstly, cancer prevention is to identify the disease at an early stage in the mass screening of the population. For this purpose, chest X-rays, mammography, and cervical swabs are used. Another task of prevention is to create the optimal conditions for the existence of people with the minimization of environmental pollution, with a decrease in the probability of contact with the body of "carcinogenic factors", and the general health of the population (Moore, 2007, p. 135). Such measures can significantly reduce the incidence of cancer.
The treatment of malignant tumors is performed by various methods depending on the nature of the tumor, its localization, and the steps of the processes. Undoubtedly, surgery is the oldest method of treatment of tumors. Along with this, ray methods of treatment have received considerable attention in recent years. The methods of drug treatment of tumors, including "hormone therapy, the use of various so-called "anticancer chemotherapeutic agents", antibiotics, etc., have been actively studied in recent decades (Colao, Muscogiuri, & Piscitelli, 2016, p. 4). The methods of combined treatment of tumors, including various combinations of surgery and radiation therapy, are frequently used today too. The modern cancer treatment is a complex matter that requires not only the knowledge but also the necessary devices for radiation therapy, a variety of chemotherapeutic and hormonal agents. The use of drugs is very complex in some cases, as it requires a special equipment, such as devices for "cardiopulmonary bypass" during perfusion of certain areas of the body where a tumor is located (Colao, Muscogiuri, & Piscitelli, 2016, p. 2).
Conclusions
Cancers are the most dangerous group of diseases today. The risk of cancer cells is that they are able to affect any organ or system of human body. To date, there is no single effective method of cancer treatment. Instead, there is a number of methods that are well effective in providing properly and timely combination of radiotherapy, immunotherapy, and chemotherapy. The numerous researches confirm that the main causes of cancer cells are in the influence of the environment on human. Every year, millions of people die of cancer, although the methods of treatment and prevention have long been known. The timely diagnosis and detection of cancer in the first two stages remain the main reasons for the success in cancer treatment.
References
Colao, A., Muscogiuri, G., & Piscitelli, P. (2016). Environment and Health: Not Only Cancer. International Journal Of Environmental Research And Public Health, 13(7), doi:10.3390/ijerph13070724
Espina, C., Straif, K., Friis, S., Kogevinas, M., Saracci, R., Vainio, H., & Schüz, J. (2015). European Code against Cancer 4th Edition: Environment, occupation and cancer. Cancer Epidemiology, 39(Supplement 1), S84-S92. doi:10.1016/j.canep.2015.03.017
Moore, G. S. (2007). Living with the Earth: Concepts in Environmental Health Science. Boca Raton, FL: CRC Press.
Pierce, J., & Jameton, A. (2003). Ethics of Environmentally Responsible Health Care. Cary, US: Oxford University Press, USA. Retrieved from http://www.ebrary.com
