What substance makes cancer

Cancer Rates and Mortality, Types and Causes: A Synthesis


The following text is a factual synthesis of reports on cancer from global health organizations (including the World Health Organization WHO1 and the International Agency for Research on Cancer (IARC)2 , the US National Institute of Health (NIH, US) and the US National Cancer Institute3, the French medical research and development organization INSERM4, as well as the British charity to fight cancer "Cancer Research UK"5). It sheds light on the development of cancer rates and the mortality associated with them and described in these reports as well as the main types of cancer and the main known causes and preventive measures.

Are global human cancer rates increasing worldwide?

It is important to distinguish between cancer incidence, i. H. the number of diagnosed cases, and cancer-related mortality or mortality. As the population ages and age is one of the main risk factors for cancer, the overall number of cancer cases is increasing. However, earlier discovery and more effective treatments also mean that while the number of cases is increasing, mortality is decreasing - at least for some cancers such as breast cancer6.

According to WHO1 The reason for the predicted sharp increase in new cases - from 10 million new cases globally in 2000 to 15 million in 2020 - is mainly due to the steadily aging population in both industrialized and developing countries, and the current trend in the Spread of tobacco use and an increasingly common unhealthy lifestyle.

What are the most common cancers in the world?

According to the World health organization (WHO)7 published statistics, around 14 million new cancer cases were discovered and 8.2 million people died of cancer in 2012 (last global statistics available); thus it was a leading cause of morbidity and mortality worldwide.

The 6 most common fatal cancers recognized by WHO are:

  • Lung cancer: 1,590,000 deaths
  • Liver cancer: 745,000 deaths
  • Stomach cancer: 723,000 deaths
  • Colon cancer: 694,000 deaths
  • Breast cancer: 521,000 deaths
  • Esophageal cancer: 400,000 deaths

In men, the most common cancers diagnosed in 2012 are lung, prostate, colon, stomach and liver cancers. In women, the five most commonly affected organs were the breast, intestines, lungs, cervix, and stomach. In the area of ​​work-related cancer, lung cancer, mesothelioma (usually associated with exposure to asbestos) and bladder cancer were most common.

The number of new cases is expected to increase by 70% over the next 2 decades. According to the IARC8 the estimated rate of future cancer exposure around the world could be much higher than is currently believed. The reason for this is the appropriation of the western lifestyle in developing countries, i. H. Smoking behavior, poor nutrition, sedentary lifestyle, and reproductive factors (Age at menarche; age at first pregnancy; age at onset of menopause, length of breastfeeding phase, effects of hormone administration).

Lung, breast and colon cancers associated with these factors are on the rise in economically developing countries. Cancer rates, common in the countries of the western world, will continue to rise in these countries unless widespread preventive measures are taken.

What are the main drivers of cancer risk worldwide?

It is usually not possible to say with certainty why someone will develop cancer and others will not, but there are known factors that increase the risk of cancer. About a third of all cancer deaths can be linked to five major diet and behavior-related risk factors:

  • Smoke is by far the easiest cause of death in the world to avoid. Tobacco is the largest risk factor for cancer and is responsible for around 20% of all deaths from cancer and around 70% of all deaths from lung cancer. Most of the world's smokers live in low- and middle-income countries.
  • alcoholism causes an estimated 6% of all deaths worldwide, with cancer causing about 1 in 8. The prevalence of alcoholism is highest in Europe and America.
  • Unhealthy diet, e.g. For example, too little fruit and vegetables and too much salt are among the main risk factors for deaths from cancer worldwide. They are becoming more common in low and middle income countries.
  • The appearance of Overweight and obesity increases particularly in low- and middle-income countries. Overweight and obesity are major causes of death worldwide.
  • Infections account for 18% of the global cancer burden, with the proportion significantly higher in low-income countries. Mainly cervical cancer from human papilloma virus (HPV) and liver cancer from hepatitis B (HBV) and hepatitis C (HCV) viruses.

As mentioned earlier, is aging Another fundamental factor in the development of cancer, probably due to the accumulation of increasing risks for certain types of cancer with age combined with the decreasing efficiency of cellular DNA repair mechanisms as humans age.

According to the WHO, 19% of all cancer cases worldwide are also so-called external "environmental causes" assign. These include air pollution, exposure to UV radiation, smoke generation from the use of solid fuels in the home and exposure to radon in closed rooms. These represented around 2% of the causes of cancer in 2008 and lead to 1.3 million deaths each year.

What role does heredity play in cancer development?

Like the WHO9 underlines, genes play very different roles. There are genes that completely determine the stage of disease (disease genes) and there are genes that interact with other genes and environmental factors to cause cancer (disease-causing genes).

In fact, the proportion of cancer that is directly caused by genetic inheritance is small, less than 5% in breast cancer and even less in other cancers. The only exception is retinoblastoma in children.

Studies have shown that the primary determinants for most cancers are lifestyle and environmental factors, rather than inherited genetic factors. However, the different ways in which chemicals are converted by the body when they are eliminated (their “metabolism”), which is genetically controlled, may also explain the differences in why some people are prone to cancer.

How does cancer develop?

The WHO10 explains that the transformation of a normal cell into a cancer cell occurs in numerous steps, usually starting with a precursor lesion and ending with a malignant tumor. Cells are subject to metabolic and behavioral changes that lead to their uncontrollable multiplication. These changes can be either mutations in the gene itself or in its expression in the cell. They are the result of the interaction of a person's genetic factors (family history can be an indicator of genetic risk factors) and external causes, such as the level of exposure to certain radiation, chemicals or infectious agents.

Does Exposure To A Known Carcinogen Always Lead To Cancer?

Any substance that causes cancer is classified as a carcinogen. Like the U.S. National Cancer Institute (NIH)11 however, the fact that a substance is determined to be a carcinogen does not necessarily mean that exposure to that substance leads to cancer. Many facts influence whether a person exposed to a carcinogen will develop cancer; this includes the amount and duration of exposure as well as the genetic background of the person. Cancer caused by involuntary exposure to environmental carcinogens is more likely to occur in subgroups of the population, e.g. B. in the case of employees in certain branches of industry who come into contact with carcinogens for work-related reasons.

AflatoxinsCoal tar and coal tar pitchNickel compounds
Aristolochic acids (from herbs and plants)Coke oven emissions radon
arsenic Crystalline silica (respirable size)Passive smoker (tobacco smoke in the ambient air)
benzeneEthylene oxideStrong inorganic acid mist with sulfuric acid
berylliumChromium VI compoundsVinyl chloride
13-butadieneIndoor emissions from coal burning in the householdWood dust
cadmiumMineral oils: untreated or poorly treatedWood dust

Most cancer risk factors (and protective factors) are first identified in epidemiological studies.In these studies, scientists look at large groups of people and compare the risk factors (lifestyle, occupation, etc.) of those who develop cancer to those who do not. These studies can show that people who develop a certain type of cancer are more or less likely to behave in certain ways or be exposed to certain substances than those who do not develop cancer. But these studies, the American Cancer Society points out12, cannot in and of themselves prove that a certain behavior or substance causes cancer. For example, the result could be random or the real risk factor could be different from what you expected. However, such discoveries can sometimes attract media attention and lead to misconceptions about how cancer develops and spreads. (More information is available on the page Common Cancer Myths and Misconceptions American Cancer Society's Known Cancer Myths and Fallacies.)13

How can exposure to carcinogens be limited and is prevention an efficient way of avoiding cancer?

Even if a substance or strain is known or suspected to cause cancer, it does not necessarily mean that it can or should be prevented at all costs. For example, the hormone estrogen that occurs naturally in the body is known to be carcinogenic. Exposure to ultraviolet (UV) radiation from sunlight is also known to be carcinogenic (melanoma). However, UV radiation is required for the production of vitamin D, so avoiding the sun entirely is neither practical nor advisable.

These substances also include many commonly used drugs, especially some hormones and drugs used to treat cancer. Tamoxifen, for example, increases the risk of developing certain types of uterine cancer, but it may be useful in treating some types of breast cancer, which may be more important for some women14.

Regulations have been issued around the world regarding exposure to known carcinogens in the workplace. Outside of the workplace, people can also take steps to limit their exposure to known carcinogens. For example, they could check their basement for radon, quit smoking, avoid exposure to the sun, or maintain a healthy weight.

For prevention there are two main ways: Primary prevention, d. H. Avoidance of stressful risk factors, and Secondary prevention, d. H. early detection of cancer through preventive examinations. The first route is the cheapest from a public health standpoint, but the second is essential if the chances of survival for people with cancer are to be increased.

How do organizations determine which substances can cause cancer?

With regard to regulatory classification, the term “hazard” refers to the substance's (physical, chemical, biological) properties - its ability to cause harm - while the term “risk” also refers to the likelihood and extent of exposure to the substance considered as dangerous substance15.

This can lead to different classifications, including the carcinogenic effects, depending on whether the risk is included as a factor in the classification or not.

The International Agency for Research on Cancer IARC classifies substances only according to their potential to cause cancer ("danger or hazard").

Specifically, the IARC has assessed over 900 substances or processes. These were then classified according to the following scheme16

Group 1Carcinogen for humans118 fabrics
Group 2AProbably carcinogenic to humans79
Group 2BPotentially carcinogenic to humans 290
Group 3Not classified for human carcinogenicity 501
Group 4Probably not carcinogenic to humans 1(*)

Typically, every country has organizations or agencies involved in carcinogen risk management programs, often in relation to specific types of cancer (e.g. breast, prostate cancer, etc.) or sectors (air, water, business). In Europe, for example, the European Food Safety Authority (EFSA) deals with potential carcinogens related to food and food production (e.g. pesticide residues).

In the case of workplace pollution, authorities such as the US or the European Agency for Safety and Health at Work (OSHA)17 specific lists are drawn up to limit exposure to these substances and other harmful chemicals and substances.