12 октября 2015г.
Cancer is one of the most widespread illnesses which conquered practically the whole world. It is known as a harmful neoplasm. This is a kind of harmful tumor that is developing from the cells of epithelial tissue (for instance, skin, mucous membrane and many other internal organs). In other words, cancer is a broad group of diseases involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invading nearby parts of the body. It may also spread to more distant organs through the lymphatic system or bloodstream. Not all tumors are cancerous; some of them do not invade neighboring tissues and do not spread throughout the body. There are over 200 different known cancers that affect human [1].
The causes of cancer are different, complicated and only in few cases understandable. Many things are known to increase the risk of cancer, including tobacco use, dietary factors, certain infections, exposure to radiation, lack of physical activity, obesity and environmental pollutants. These factors can directly damage genes or combine with existing genetic faults within cells to cause cancerous mutations [1].
Approximately 5–10% of cancers can be traced directly to inherited genetic defects. Many cancers could be prevented by not smoking, eating more vegetables, fruits and whole grains, eating less meat and refined carbohydrates, maintaining a healthy weight, exercising, minimizing sunbathes and being vaccinated against some infectious diseases [1].
Cancer can be detected in a number of ways, including the presence of certain signs and symptoms, screening tests or medical imaging. Once a possible cancer is detected it is diagnosed by microscopic examination of a tissue sample. Cancer is usually treated with chemotherapy, radiation therapy and surgery. The chances of surviving from the disease vary greatly by the type and location of the cancer and the extent of disease and the start of treatment. While cancer can affect people of all ages, a few types of cancer are more common in children. But still the risk of developing cancer generally increases with age. In 2007, cancer caused about 13% of all human deaths worldwide (7.9 million people). Rates are rising as more people live to an old age and as mass lifestyle changes occur in the developing world [1].
Cancers are classified by the type of cell or by the origin of the tumor. These types include:
· Carcinoma: Cancers derived from epithelial cells. This group includes many of the most common cancers, particularly in the aged, and include nearly all those developing in the breast, prostate, lung, pancreas, and colon.
· Sarcoma: Cancers arising from connecting tissue (for example, bone, cartilage, fat, nerve), each of which develop from cells originating in mesenchymal cells outside the bone marrow.
· Lymphoma and leukemia: These two classes of cancer arise from hematopoietic (blood-forming) cells that leave the marrow and tend to mature in the lymph nodes and blood, respectively. Leukemia is the most common type of cancer in children accounting for about 30%.
· Germ cell tumor: Cancers derived from pluripotent cells, most often presenting in the testicle or the ovary (seminoma and dysgerminoma, respectively).
· Blastoma: Cancers derived from immature "precursor" cells or embryonic tissue. Blastomas are more common in children than in older adults [1].
Some types of cancer are named for the size and shape of the cells under a microscope, such as giant cell carcinoma, spindle cell carcinoma, and small-cell carcinoma [1].
The logistic problems and costs encountered with cohort studies have led to the development and increase in popularity of another type of study: the case–control study. In these studies, the epidemiologist compares a group of individuals who have the disease under investigation (termed ‘cases’—e.g., persons with lung cancer) with a group without that disease (termed ‘controls’), to see whether the groups differ in their past history of exposures (e.g., smoking habits). This is the reverse of the time-sequence adopted in cohort studies. This technique of looking retrospectively is used daily by clinicians when they take case histories [4].
One of the earliest studies to make use of the case–control approach was that reported by Broders (1920) on squamous cell epithelioma of the lip in relation to pipe smoking. Unfortunately, Broders failed to describe the method by which he selected the controls. In 1926, Lane-Claypon reported a case–control study of the role of reproductive experience in the etiology of breast cancer. This report is particularly important because it emphasized the need to use a control group for comparison with the cases, and discussed methods for selecting hospital controls to address specific hypotheses [4].
A more recent development has been the application of epidemiological principles and methods to the design, conduct and analysis of intervention trials [4].
This type of controlled experiment (case-control) has become an integral part of the evaluation of new preventive and therapeutic agents and procedures. For instance, the intervention trial has been used to evaluate the impact of anti-smoking advice on health (Rose & Colwell, 1992), to assess the role of health education programs in preventing oral cancer in India (Gupta et al., 1986), to evaluate screening programs for breast cancer (e.g., Shapiro et al., 1971), and to assess the efficacy of hepatitis B vaccination in preventing liver cancer (e.g., Gambia Hepatitis Study Group, 1987) [4].
It is obvious from the low survival from many cancers that if these diseases are to be controlled, we cannot rely solely on increasing the availability of medical care. It is vital to increase our understanding of the genetic, environmental and social factors that foster these diseases, with the aim of applying this knowledge to effective preventive measures. The ultimate goal of cancer epidemiology is to identify risk factors so as to allow the early introduction of effective preventive measures. To achieve this goal, however, cancer epidemiology requires a multidisciplinary approach, bringing together clinicians, laboratory and social scientists, and public health and other health-related professionals [4].
The growth in our knowledge of cancer biology has led to remarkable progress in cancer prevention, early detection, and treatment. Scientists have learned more about cancer in the last 2 decades than had been learned in all the centuries preceding. This does not change the fact, however, that all scientific knowledge is based on the knowledge already acquired by the hard work and discovery of our predecessors – and we know that there is still a lot more to learn [3].
According to World Health Organization, every year more than 7,5 million people in the world die because of oncological diseases. It is very interesting to know that by the end of 2012 there were more than 3 million patients in Russian oncological centers and over the last 10 years the number of oncological patients in the country increased by 25,5%. In 10 years – if the situation doesn’t change– the level of patients will raise over 15-20%. Annual economic damage from oncological diseases is more than 90 billion rubles [1].
The high death rate in Russia is caused by late identification of illnesses and cancer is not an exception. Diagnoses are made when treatment is already difficult, expensive and hopeless. Every third cancer patient in Russia dies within a year after diagnosis.
The situation in America is completely different. In this country more than 80% of patients survive not only in the first year, but also completely recover and pass a five-year boundary after diagnosis statement. Thus, the tumor is found at the first or second stage, instead of the third or fourth, as it is in our country [1].
For my research I made an interrogation. The question that I asked to students of Perm State Pharmaceutical Academy was: «Do you know how cancer can be detected? » Frankly speaking, the results were inconsolable: 45% of polled students answered: “I don’t know”; 27% knew that tumor can be detected by tumor; 20% said that we can fix by special short wind, cough, hoarseness and only 8% stated that the causeless loss of weight can be the reason of cancer. The biggest part of students is not able to determine cancer & this fact should be taken into account.
I suppose practically everyone knows that the symbol of fighting with such an awful disease is a tape. But I’m sure that not an each person is aware of the fact that the colour of tape depends on the type of cancer. For example, black tape symbolizes melanoma, emerald green – liver cancer, pink – breast cancer etc.
In conclusion I’d like to say that cancer is growing day by day. Everyone is under the sight of this illness. It’s extremely hard to resist it alone. Let’s prevent and fight with cancer together, because together we can do even impossible things.
List of references
1. Режим доступа: http://en.wikipedia.org/wiki/Cancer
2. Режим доступа: http://www.cancer.org/cancer/cancerbasics/thehistoryofcancer/
3. Режим доступа: http://www.cancer.org/cancer/cancerbasics/thehistoryofcancer/the-history-of-cancer-twenty-first-cent...
4. Режим доступа: http://www.iarc.fr/en/publications/pdfs-online/epi/cancerepi/CancerEpi-1.pdf
