Cancer as One of the Most Highly Prevalent Diseases in Modern Times: Various Types of Cancers Among Humans - Research Paper Example

Cancer is a term used to refer to a group of diseases and it is one of the most highly prevalent diseases in modern times. The disease occurs mainly due to uncontrolled abnormal cell growth and their invasion of various tissues of the body. This mainly occurs due to various mutations that take place at the DNA level of the cell. This in turn affects that normal division and multiplication of the cell which results in the formation of a mass of cells referred to as a tumor. A tumor is said to be cancerous if it moves from its place of origin to nearby tissues and other parts of the body through blood or lymph. In this case it is referred to as a malignant tumor. However, it could also be benign, wherein they do not spread, they can be removed through surgery and relapse is less compared to the malignant form. Blood and bone marrow cancers do not form tumors. Based on the cell or tissue where the cancer originates, cancers are classified into broad categories such as carcinoma, lymphoma, myeloma, sarcoma, leukemia and central nervous system cancers. Till date there are more than 100 different types of cancers that have been identified (Ramsohok, 2009). Epidemiological studies in cancer were done as early as the 1700’s. The reason for the occurrence of breast cancer and scrotal cancer were the ones that were initially explored. In one such study, the increased occurrence of scrotal cancer among chimney sweeps was attributed to their working lifestyle which made them susceptible to the disease after reaching puberty. A comparative study also suggested that the use of protective clothing by these individuals reduced the occurrence of the disease. Another study suggested that the increased occurrence of breast cancer among nuns was due to their celibate life. However, development in the field of statistics made it possible to classify the various types of cancer and also determine their pattern of occurrence among different populations. A more comprehensive research on various types of cancers among humans was done after World War II, especially with respect to the role of environmental agents in causing cancer. Many studies that examined the exposure to various chemicals and smoke such as cigarettes and its relationship with lung cancer were studied and many comparative studies with different populations were carried out. Most of these were cohort studies in which the disease occurrence in people who were exposed to certain agents and those who were not exposed to the same was compared. Owing to the increased costs of cohort studies, control studies were introduced wherein the exposure history of a control population who did not have the disease was compared with those who had the disease. This is now considered to be ideal to study cancer like diseases. Such control studies have revealed the association between breast cancer and late first birth, papillomavirus infection and cervical cancer and many more. In addition these studies are becoming increasingly useful for studying the effectiveness of various therapeutic treatments that are now available for cancer such as drugs, radiation and currently vaccines. Thus cancer epidemiology plays a vital role both in understanding the disease as well as in determining the effective treatment options, however, more research needs to be done to completely understand the genetic and biological basis of the disease which will help to identify the risk factors and thus aid in choosing effective treatment options (Silva, 1999, p.1-10). According to the estimates provided by the National Cancer Institute’s Surveillance and Epidemiology and End Results (SEER) database of 2002, the annual incidence of cancer is about 1,248,900 cases with an incidence rate of 1 in 217 people. The number of people newly affected by cancer within a time period is reflected in the data provided by SEER. Among the various types of cancer, there is increased prevalence of breast, colon, lung and prostrate cancer in the US (Cancer Prevalence, 2008). The major causative factors for most cancers are still unknown excepting a few such as lung cancer. However, the risk factors that make an individual susceptible to a type of cancer are fairly clear and educating people about this could help in prevention. Both environmental and genetic factors contribute to susceptibility. Most of the environmental risks are occupational hazards such as exposure to aniline increases risk of bladder cancer, working in mines and with asbestos increases risk of lung cancer, working in nickel increases risk of nasal cancer, exposure to benzene at prolonged intervals may cause leukemia. In addition excessive exposure to natural radiation like sunlight increases risk of developing skin cancer, especially evident among farmers. Other lifestyle associated factors such as cigarette smoking increases risk of developing lung cancer. Increased alcohol has been found to be involved in the onset of head, neck and esophageal cancer and liver cancer. Colon, liver and stomach cancers have been associated with dietary habits. Breast cancer among women occurs when the women has had a late pregnancy, an early menarche or a late menopause. Cervical cancer is highly prevalent among sex workers and those who have vaginal infections. Additionally immunosuppressive drugs and alkylating agents have also been implicated in causing cancer. Increased production of hormones within the body can cause breast or endometrial cancer. Inheritance of cancer causing genes predisposes the individual to that form of cancer and this is evident in case of breast cancer and also in other common cancers such as colon and stomach cancers. Another well studied form of cancer which is thought to have a genetic origin is retinoblastoma. Alteration of genes involved in normal cell growth and division by radiation and other environmental agents may transform them into an oncogene that could cause cancer by initiating uncontrolled cell proliferation of normal cells. Finally the role of viruses such as human T-lymphotrophic virus and Epstein Barr virus as a causative factor for cancer are being proven (The Etiology of Cancer). Screening and diagnosis of cancer are vital to effective treatment. Prior to formal diagnosis, screening tests are done to detect the presence of cancer before onset of any symptoms. This is usually done if there is a familial history of cancer. However, screening tests may sometimes produce false-positive results. Some common screening tests that can be performed include testing for prostrate-specific antigen levels for prostrate cancer, occult blood test in stools for solon cancer, pap test for cervical cancer, mammography for breast cancer, and to some extent determination of the presence of tumor markers in the blood for certain cancers. If the presence of cancer is detected further diagnostic tests may include imaging studies such as CT scan or an ultrasonography or x-ray which will aid to determine the location of the tumor and its size. Confirmation is usually done by taking a biopsy of the tissue sample from the determined location. This is followed by staging, which determines the extent of spread of the cancer and this could be done using scanning techniques. Biopsies of tissue samples can also be done to determine the spread of cancerous cells (Fury, 2006). The signs and symptoms of cancer depend on its location, its growth and whether it has metastasized. There can be specific symptoms as well as general symptoms. If the cancer growth is adjacent to blood vessels, its growth can create some pressure on the vessels and these can give rise to certain symptoms. In some cases it can block the flow of certain substances that may cause symptoms. Constipation, changes in stool and pain or blood in urine can signal the presence of colon or bladder cancer. Prolonged indigestion can signal the presence of stomach cancer. Skin sores in the oral cavity due to prolonged periods could be due to oral cancer. Blood in the sputum or cold and cough for prolonged periods and vaginal bleeding could signal presence of lung cancer and vaginal cancer respectively. However the general symptoms of cancer include, unexplained weight loss, tiredness and fatigue. This is mainly because the cancer cells use the body’s energy resource for its growth or it may itself release certain substances that could cause harm to the body. Other symptoms include pain and skin changes such as darkening of the area or reddening due to itching. Other symptoms may also be associated with the general immune response of the body. Many of these general symptoms can be confused with other disorders. Hence a through medical examination will help determine the presence and extent of cancer (Signs and Symptoms, 2009). Cancer prognosis will enable the patient to have an idea about the course and outcome of the disease, whether the treatment undertaken will result in complete cure as well as the chances of recurrence for that particular treatment. Prognosis trials compare existing treatment methods with the newer ones only. Hence it is quite different to determine the prognosis if no treatment is given to the patient. It is only the doctor who can assess the correct prognosis in such conditions and advice the patient accordingly (Understanding Prognosis). There are four standard treatment methods for cancer, chemotherapy, radiation therapy, surgery and biological therapy. The oncologist would decide upon the ideal treatment choice for a given type and stage of cancer and should discuss the treatment process with the patient. One of the most common and most sought after treatment procedure is chemotherapy or rug treatment, which targets and kills rapidly proliferating cancer cells. However, this is not site-specific and as a result other rapidly multiplying cells in the body such as hair follicle cells are affected by this treatment method. Additionally there are also other side effects such as fatigue, lack of sexual interest and stomach related problems. Radiation therapy uses radiation energy to shrink and eliminate tumors. Nearby cells can also be damaged in the process. This may be given in combination with other treatments such as chemotherapy. Depending on the growth of the tumor, surgical removal of the tumor may also be carried out. This could also be combined with chemotherapy or radiation therapy. The biological treatment methods work by inhibiting the biological mechanisms that allow for the cancer to develop like blocking oxygen supply to the particular tissue thereby killing the cells (Fayed, 2009). Various studies have been carried out to determine the effectiveness of the above treatments. Imaging studies such as positron emission tomography are currently being employed to study the effect of chemotherapy and other such treatments in cancer tissues. In addition studies have also determined that a lack of the tumor suppressor protein p53 and a gene called MEF in a cell makes them more susceptible to treatments such as chemotherapy and radiation. Hence an early determination of the effectiveness of a particular treatment would help to regulate the dosage and duration of the treatment procedure, thereby minimizing the side effects (Cell’s Inactive State, 2009; Verrillo, 2007). In conclusion, cancer is an extremely difficult disease to fight especially if it has metastasized owing to the movement potency of the cancer cells. However, early detection of the signs and symptoms and resorting to the ideal treatment option would result in a definitive cure of the disease, due to the enormous amount of research in treatment methods that have been carried out successfully. 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