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    Cancer: Basic Facts   Manjari Peiris   One in eight deaths worldwide is caused due to cancer. Cancer causes more deaths worldwide than AIDS, tuberculosis, and malaria combined. It is the second leading cause of death in  developed countries, (following heart diseases) and the third leading cause of death in developing countries (following heart diseases and diarrhoeal diseases).   Cancer is a group of diseases characterized by uncontrolled growth and spread of abnormal cells. If the spread is not controlled, it can result in death. Cancer is caused by both external factors (tobacco, chemicals, radiation, and infectious organisms) and internal factors (inherited mutations, hormones, immune conditions, and mutations that occur from metabolism). These casual factors may act together or in sequence to initiate or promote carcinogenesis. The development of most cancers requires multiple steps that occur over many years. Certain types of cancer can be prevented by eliminating exposure to tobacco and other factors that accelerate this process. Other potential malignancies can be detected before cells become cancerous or at an early stage, when the disease is most treatable. Cancer is treated by surgery, radiation, chemotherapy, hormones, and immunotherapy.   The burden of cancer is increasing in developing countries as childhood mortality and deaths from infectious diseases decline and more people live to older ages. As people in developing countries adopt higher consumption of saturated fat and calorie dense foods, and reduced physical activity, rates of cancers common in western countries will rise if preventive measures are not widely applied.   It is estimated that by 2050, the global burden is expected to grow to 27 million new cancer cases and 17.5 million cancer deaths simply due to the growth and aging of the population.   The three most commonly diagnosed cancers in economically developed countries are prostate, lung and bronchus, and colorectal among men and breast, colorectal, and lung and bronchus among women. The three most commonly diagnosed cancers in economically developing countries are lung and bronchus, stomach, and liver in men, and breast, cervix uteri, and stomach in women. In both economically developed and developing countries, the three most common cancer sites are also the three leading causes of cancer death.   Several major cancers linked to chronic infectious conditions (including stomach and cervix) become less  common as countries become economically developed, whereas cancers related to tobacco use and Western patterns of diet, physical inactivity, and reproduction (especially lung and bronchus, breast and colorectal) increase with economic development.   Factors that contribute to regional differences in the types of burden of cancer include regional variations in the prevalence of major risk factors, availability and use of medical practices such as cancer screening, availability and quality of treatment, completeness of reporting, and age structure. Currently, two of the three leading cancers in men (stomach and liver) and women (cervix and stomach) in developing countries are related to infection. Stomach cancer continues to be the most common infection-related cancer worldwide, followed closely by liver and cervix. Approximately 15% of all incident cancers worldwide are attributable to infections.  This percentage is about three times higher in developing countries than in developed countries.   The frequency of commonly diagnosed cancer cases or deaths also varies by geographic areas, and countries and parishes within countries.   It is estimated that more than half of all new cancers and cancer deaths worldwide are potentially preventable. Cancers related to tobacco use, heavy use of alcohol and obesity are most effectively prevented through a combination of education and social policies that encourage healthy behaviours and discourage unhealthy practices. Certain cancers that are related to infectious agents, such as hepatitis B, human immunodeficiency virus (HIV), human papilloma virus and helicobacter pylori. could be prevented through known interventions such as vaccines, antibiotics, improved sanitation, and education. Some cancers such as colorectal and cervix can be avoided by detection and removal of pre cancerous lesions through regular screening examinations by a health care professional.   Early detection of cancer is important, as it provides a greater chance that treatment will be successful. Cancers that can be detected at an early stage through screening include breast, cervix, colorectal, prostrate, oral cavity, and skin. Screening has been proven to be effective in reducing the severity of disease and mortality for all of these sites except prostate and skin. Screening and early treatment services for most of these cancers are not available in developing countries because of limited resources.   The risk of being diagnosed with cancer increases with age, though anyone can develop cancer. Of the newly diagnosed cancer cases in developed countries 78% were at age 55 and over. In developing countries it was 58%. The difference is largely due to variations in age structure of the populations. The populations of developing countries are younger and have a smaller proportion of older individuals in whom cancer most frequently occurs.   Cancer researchers use the term “risk” in two common ways, i.e. lifetime risk or relative risk. Lifetime risk refers to the probability that an individual will develop or die from cancer over the course of a lifetime.   Relative risk is a measure of the strength of the association between a risk factor and a particular type of cancer. It compares the risk of developing cancer in persons with a certain exposure or trait to the risk in persons who do not have this characteristic. Male smokers are about 23 times more likely to develop lung cancer than nonsmokers, thus their relative risk is 23. Most relative risks are not that large.  A woman with a history of breast cancer (mother, sister, or daughter) has about twice the risk of developing breast cancer compared to women who do not have a family history.   Most of the genetic abnormalities that affect cancer risk are not hereditary, but result from damage to genes that occur throughout one’s lifetime. Damage to genes may be due to internal factors, such as hormones or the metabolism of nutrients within cells, or external factors, such as tobacco, chemicals, and sunlight. It is estimated that 5-10% of all cancers are strongly hereditary, meaning that individuals who inherit a specific genetic alteration have a very high risk of developing a particular cancer. It is thought that many cancers result from a combination of hereditary and environmental factors.   The total number of cancer survivors in the world is unknown. Information of cancer registries and survival are not on record. But the International Agency for Research on Cancer estimates that in 2002 there were approximately 24.6 million cancer survivors worldwide who had been diagnosed within the past five years. Some of these individuals were cancer free, while others still had evidence of cancer and may have been undergoing treatment. The number of people with a history of cancer in the coming years is expected to increase with the improvements in survival as well as the anticipated growth and aging of population.   Survival from a specific cancer is usually measured as the proportion of people diagnosed with cancer who are still alive five years after diagnosis. Cancer survival rates in a population are affected by a number of factors, most importantly, the type of cancer that occur, the stages at which cancers are diagnosed, and whether treatment is available.   There are large survival differences between developed and developing countries. This difference is mostly due to the greater availability of early detection and more effective treatments in the respective countries. It is also due, in part to detecting some cancers earlier in the course of disease through screening and detecting some cancers that might not progress. Similar worldwide variations are noted for cancers of the colon, uterine, cervix, and prostrate, also for which both early detection and improved treatment are responsible for improved survival. In regard to childhood and other cancers, availability of treatment is mainly responsible for better survival in developed countries.   Primary prevention is currently the most effective defense against cancers with known risk factors.   To ascertain the extent or spread of the disease at the time of diagnosis staging is necessary. A number of different staging systems are used to classify tumors,   The financial cost of cancer is substantial. They are indirect costs (expenditure on resources and treatment, rehabilitation related to the illness, loss of economic output due to days of missed work, premature death etc. There are also hidden costs. With the growth and aging of the population, prevention efforts are important to help reduce new cancer cases, human suffering and economic costs.   Successful national cancer control policies and programs raise awareness of cancer, reduce exposure to cancer risk factors, provide information and support for the adoption of healthy lifestyles, and increase the proportion of cancers detected early.   The World Health Organization recommends that four broad approaches based on the economic development of a country should be taken into consideration when developing national strategies for controlling cancer.   They are Primary Prevention where exposure to cancer causing factors such as tobacco use, nutrition, physical inactivity, occupational exposures, and chronic infections should be eliminated. Primary prevention offers the greatest public health potential and the most cost effective long term method of cancer control.  Approaches to primary prevention include immunization against infectious agents that cause certain cancers, effective tobacco control measures, reduction of alcohol consumption, maintenance of healthy body weight and physically active lifestyles, dietary interventions, sun/UV avoidance, reduction in occupational exposure to carcinogens and pharmacological interventions.   The main objective of Early Detection and Secondary Prevention through screening is to detect pre-cancerous changes or early stage cancers when they can be treated most effectively. Early detection is only valuable if it leads to timely diagnostic follow up and effective treatment. There are two strategies for early detection, opportunistic screening requested sporadically by a physician or an individual or organized screening in which a defined population is contacted and invited to be screened at regular intervals.   The first step to cancer management is diagnosis including careful clinical and pathological assessments. Once a diagnosis is confirmed it is necessary to determine cancer stage, where the main goals are to aid in the choice of therapy, to determine prognosis and to standardize the design of research treatment protocols. The primary modalities of cancer treatment are surgery, chemotherapy, and radiotherapy. These treatments may be used alone of in combination.   The majority of cancer patients present with advanced disease. The only realistic treatment option then is pain relief and palliative care.  The World Health Organization has developed guidelines for cancer pain management. It has also elaborated guidelines for assessing national drug policies to ensure availability of opioids for medical and scientific use.  The WHO has played an important role in encouraging effective pain management and monitoring the availability of opioids internationally.   Data for this article was obtained from the American Cancer Society You can read also about order lipitor online