What kind of disease is cancer? Part 2

Risks and myths

Atlas company blog, Geektimes

In the first article about cancer, we told you what kind of disease it is and how it develops. After reading, many people had a question about what affects the development of a malignant tumor. Today, the experts of the Solo project of the Atlas biomedical holding will talk about real and mythical factors that increase the risk of cancer.

What doesn't cause cancer

Let's start with the myths and tell you what factors do not affect the risk of developing a tumor.

Genetically modified foods 
Genetically modified foods are foods in which one or more genes have been altered. There is a misconception that GM foods affect the human genome. This misconception originates from Seralini's scientific work, in which there were many inaccuracies and errors. Repeated studies have not confirmed that genetically modified foods cause cancer.

Artificial sweeteners  The most common sugar substitutes – saccharin and aspartame – were considered carcinogens in the XX century.
Aspartame was associated with the appearance of a brain tumor, and because of saccharin, rats developed a bladder tumor. But clinical studies have refuted the link between artificial sweeteners and the development of malignant tumors.

Dairy products  Cow's milk contains insulin-like growth factor (IGF-1), progesterone and estrogen.
It was assumed that they affect the level of hormones in the human body, which may increase the risk of cancer. Today there is no reliable data to say exactly how the consumption of milk affects the risk. Dairy products may increase the risk of prostate cancer, but reduce the risk of colorectal cancer and bladder cancer. More detailed research is needed to make sure of this.

Sugar  There is no evidence that sugar affects the incidence of malignant tumors.
Sugar or glucose is the fuel for all the cells of our body. It is impossible to regulate glucose levels so that only healthy cells get it. However, sugar consumption indirectly affects the development of the tumor. Due to the high calorie content, sweet food can lead to obesity, which increases the risk of developing malignant tumors.

Termination of pregnancy  Termination of pregnancy disrupts the normal functioning of female sex hormones, so it has been suggested that abortions may increase the risk of breast cancer.
But in the course of research, it was found that termination of pregnancy does not affect the risk of developing breast cancer.

Microwave popcorn  Microwave popcorn packaging contains a non-stick layer.
During cooking, a substance is released from it, which, when inhaled, increases the risk of lung cancer. However, the increased risk is recorded only among employees of popcorn factories. In ordinary life, the risk will not increase, even if we assume that a person can only eat popcorn. If you are afraid of harmful effects, do not open the package immediately after cooking, let the popcorn cool down a little. Then dangerous volatile substances will settle and will not harm the body.

Environmental factors that increase
the risk of developing malignant tumors (cancerprogressreport.org )

Smoking

Smoking is one of the most significant factors affecting the development of a tumor. 

A cigarette is a small factory, the smoke of which contains about 7 thousand chemical compounds. It has been proven that 93 of them are dangerous to human health. With each puff, the solid particles contained in the smoke fall on the surface of the epithelium of the mouth, throat and lungs. The body cannot remove them, so the more a person smokes, the more carcinogens settle in the tissues. 

Carcinogenic substances damage the DNA of healthy cells, which leads to the formation of mutations. Basically, damage accumulates in the cells of the lungs, larynx, pharynx and oral mucosa, but mutations also occur in the cells of the bladder and liver. 

The resins in tobacco smoke inhibit the immune system, so it recognizes and destroys malignant cells worse. This is another reason for the high risk of developing cancer.

You can often hear the misconception that smoking hookah is not as harmful as regular cigarettes. Hookah contains more carbon monoxide, nicotine and tar. A hookah smoker takes about 200 puffs per hour, whereas one cigarette takes 10-13 puffs. Therefore, while smoking a hookah, a person consumes much more harmful substances than when smoking cigarettes. 

There is a myth that smoking pipes and cigars is safer than smoking regular cigarettes. But research shows that the harmful effects of cigars and pipes are no different from regular cigarettes.

The surrounding tobacco smoke, which other people breathe next to the smoker, also contains dangerous carcinogens. They contribute to the formation of mutations in the cells of the respiratory tract, even in a non-smoker. 

Every year around the world, passive smoking causes about 21 thousand cases of fatal lung cancer. To protect yourself and your loved ones from smoke, do not allow others to smoke near you in the house, car and other enclosed spaces. Children's bodies are particularly susceptible to the harmful effects of tobacco smoke, so do not allow smokers to be near children.

Fatness

Obesity is the second cause of the development of malignant tumors after smoking. 

Overweight people have a higher risk of developing cancer of the esophagus, thyroid gland, stomach, liver, kidney, brain, pancreas and breast, gallbladder, endometrium, ovaries and colorectal cancer.

There are several mechanisms of the influence of excess weight on the development of a tumor: 

• People with obesity develop chronic inflammation, which the immune system is constantly fighting. At the same time, special substances are released that damage the DNA of healthy cells located near the focus of inflammation.

• Elevated levels of insulin and insulin-like growth factor (IGF-1) promote the growth of both healthy and tumor tissues.

• Fat cells produce large amounts of the hormone estrogen, which increases the risk of developing breast, endometrial (uterine mucosa) and ovarian cancers.

• Fat cells synthesize adipose tissue hormones (adipokines), which stimulate cell division and differentiation. The level of these hormones increases with an increase in the amount of adipose tissue in the body.

• Obesity and related changes in the microflora can affect inflammatory processes in the body and increase the risk of developing a malignant tumor. Therefore, scientists are also studying the role of intestinal microflora in the development of malignant tumors.

Viruses and infections

Some viruses and bacteria increase the risk of developing a malignant tumor. 

Human papillomavirus is a widespread virus, some types of which lead to cancer. The presence of oncogenic HPV types in the human body increases the risk of developing cancer of the cervix, anus and oropharynx. The most common oncogenic HPV types are 16 and 18.

HPV is transmitted through contact with the skin or mucous membrane of the genitals of an infected person. Proper and regular use of a condom reduces the risk of transmission of the virus. If you use a condom irregularly or incorrectly, then the probability of transmission of the virus increases.

On average, immunity takes 1-2 years to completely get rid of the human papillomavirus. During this time, benign warts may appear, but most often the virus is asymptomatic. Oncogenic HPV types are different from the rest. They stay in the body for a long time and cause cells to divide, which increases the risk of cervical cancer. 

Epstein-Barr virus is associated with an increased risk of lymphoma and nasopharyngeal cancer. The virus is transmitted through saliva during kissing, sharing a toothbrush and drinking glasses. Approximately 90% of the population has the Epstein-Barr virus. In most cases, viral infection is asymptomatic.

Hepatitis B and C viruses can lead to the development of chronic infection, which increases the risk of cirrhosis and liver cancer. The human immunodeficiency virus does not belong to oncogenic viruses, but it can cause AIDS, which increases the likelihood of malignant neoplasms. 

The bacterium Helicobacter pylori is the cause of 90% of all cases of stomach cancer in the world. 
As a rule, all bacteria in the stomach die due to the acidic environment. Helicobacter pylori can move and hide in the mucus that covers the walls of the stomach. The bacterium also secretes ammonia, which neutralizes acid and creates conditions favorable for survival. The waste products of Helicobacter pylori damage the epithelial cells of the stomach, which provokes the development of ulcers and increases the risk of cancer.

Sedentary lifestyle

The risk of developing endometrial, colon and lung cancer increases if a person spends most of the time sitting or lying down. Scientists do not yet know exactly why this is happening. The probable causes are lack of physical activity, poor nutrition and excess weight.

In many studies, it is sitting while watching TV that is associated with an increased risk of developing certain types of cancer. While watching TV, a person spends fewer calories than while reading books or working at a computer in a sitting position. In addition, scientists suggest that watching TV is associated with the consumption of high-calorie and sweet foods, which can lead to excess weight.

Unbalanced nutrition

Scientists have managed to establish a link between the development of malignant tumors and the consumption of certain foods.

Researchers have found that a large consumption of red meat cooked at high temperatures is associated with an increased risk of colorectal cancer, pancreatic and prostate cancer. 

Red meat cooked at high temperatures (more than 150 ° C) on a grill, grill or frying pan contains heterocyclic amines and polycyclic aromatic hydrocarbons (PAHs). In laboratory studies, these substances have been recognized as mutagens: they damage DNA and increase the risk of cancer. 

Most processed meat contains salts, nitrites and nitrates. When a person eats, for example, a piece of sausage, nitrites and nitrates react with other compounds in meat and can turn into nitrosamines. Nitrosamines are carcinogens and mutagens that increase the risk of cancer.

Salty foods can damage the gastric mucosa, which causes inflammation and atrophy. This creates favorable conditions for Helicobacter pylori and thereby increases the risk of developing stomach cancer. 

Hot drinks are also carcinogens. Tea, coffee or mate above 65 degrees Celsius increase the risk of esophageal cancer. Scientists suggest that this is due to damage to the epithelium.

Excessive alcohol consumption

Excessive alcohol consumption increases the risk of developing malignant tumors of the head and neck, esophageal cancer, liver and colorectal cancer. 

There are several mechanisms of the negative effects of alcohol. Firstly, alcohol acts as an irritant and damages the cells of the mouth and throat. A damaged cell can become malignant as mutations accumulate.

Secondly, the product of alcohol metabolism damages the liver. In the liver, ethanol is metabolized into acetaldehyde. It is a toxic substance that damages the DNA of cells. Also, excessive alcohol consumption leads to inflammation and scarring of the liver, which increases the risk of developing a malignant tumor. 

Thirdly, alcohol consumption in women is associated with high levels of estrogen (female sex hormone), which increases the risk of developing breast cancer.

The increased risk does not depend on the type of drink, since ethanol is contained in any type of alcohol.

Unfavorable working conditions

Some types of work are associated with an increased risk of developing malignant tumors: 

Agricultural industry. Due to exposure to the sun and agricultural chemicals.

Construction and painting works. Due to exposure to asbestos, solvents, paint, coal combustion products, exhaust gases and the sun.

The manufacturing and mining industry is associated with exposure to oil and its refined products, asbestos, coal combustion products, solvents, sunlight, industrial dust, as well as radon gas.

An increased risk of cancer among workers in the service sector may be associated with passive smoking, exposure to the sun, exhaust gases.

Some cancers are associated with exposure to specific carcinogens. For example, people who work with asbestos have an increased risk of developing lung cancer, colorectal cancer, ovarian cancer and stomach cancer.

Reproductive and hormonal factors

The risk of developing breast cancer depends on the duration of exposure and the level of female sex hormones – endogenous estrogen and progesterone. The level of these hormones increases during puberty and in the absence of pregnancy.

The early appearance of menstruation, late menopause, the late birth of the first child or the absence of pregnancy are signs of prolonged exposure to hormones. Therefore, these reproductive factors indicate an increased risk of developing breast cancer.

Exogenous hormones that enter a woman's body from the outside also increase the risk of developing breast cancer. Exogenous hormones include hormones in oral contraceptives and hormone replacement therapy preparations.

Oral contraceptives reduce the risk of endometrial cancer and ovarian cancer, but may increase the risk of breast, cervical and liver cancer. The longer a woman takes oral contraceptives, the lower the risk of developing endometrial cancer and the higher the risk of developing other types of tumors. After stopping taking oral contraceptives, the risk of developing cancer gradually decreases.

Hormones in oral contraceptives can change the susceptibility of cervical cells to human papillomavirus. Therefore, if there is an oncogenic type of HPV in the body, the risk of developing a malignant tumor increases several times. 

Hormone replacement therapy, which is used to prevent diseases during menopause, also increases the risk of developing breast cancer. Confirmation of this is a randomized controlled trial in which 16.6 thousand women participated. Among women who took hormone replacement drugs, 245 cases of breast cancer were diagnosed; among women who took placebo, 185 cases.

Ultraviolet and ionizing radiation

Ultraviolet radiation and ionizing radiation also increase the risk of developing malignant tumors.

When ultraviolet light affects unprotected skin, DNA damage occurs in the cells. If the exposure continues for a long time, sunburn appears on the skin. Redness indicates that the body is trying to repair or replace damaged cells. The same thing happens with a normal burn, but there is an important difference. When burned on something hot, there is no DNA damage, so the cells are gradually replaced with new ones.

With a sunburn, DNA damage can remain without recovery, then there will be a cell with a mutation in the skin among ordinary cells. Such cells divide and continue to accumulate more and more mutations, so they can turn into malignant tumor cells. 

Ionizing radiation also damages the DNA of cells and can cause cancer. Exposure to ionizing radiation can be encountered during X-rays, fluorography, mammography or computed tomography. These procedures are considered safe for human health, since the benefits of them exceed the small risk.

In ordinary life, a common source of ionizing radiation is radon gas. Radon is released by natural materials, such as granite, as well as soil and groundwater. Gas enters houses through cracks in floors and walls, accumulates in basements and can be contained in water. Radon is the second cause of lung cancer after smoking.

Environment

Factories, a large number of cars, as well as improper disposal of industrial waste can be associated with an increased risk of cancer.

Scientists at the University of Illinois USA have found a link between an unfavorable environmental situation and a high incidence of malignant tumors. Especially vividly polluted environment is associated with the incidence of lung, prostate and breast cancer. 

The cause of the development of malignant neoplasms due to harmful environmental substances is oxidative stress. The DNA of cells is damaged due to the oxidation reaction, which leads to the appearance and consolidation of mutations in somatic cells.

Medical preparations and procedures

Patients who have undergone radiation therapy, chemotherapy or stem cell transplantation have an increased risk of developing a new malignant neoplasm. 

Cholesterol-lowering drugs (statins) may increase the risk of tumor development among people with a predisposition to prostate and breast cancer and the elderly. However, in the case of liver cancer, statin therapy is associated with a reduced risk of tumor development.

Heredity

Heredity is a factor that we cannot influence. However, you can correctly assess the risks and carefully treat your health in order to reduce the likelihood of developing malignant neoplasms.

Most mutations that cause cancer are transmitted by autosomal dominant type: with a 50% probability, a hereditary mutation can pass from a parent to a child.

All nuclear DNA genes are contained in cells in two copies – one from each parent. If the mutation occurred only in one gene, then the second one performs its work. In this case, a person has a predisposition to malignant tumors: if the second gene is damaged, the cell can become malignant.

Many family cases of cancer are associated with hereditary mutations in tumor suppressor genes. There are more than 90 known genes that are reliably associated with hereditary forms of cancer. The risk of developing different types of malignant tumors may depend on both several genes and a set of mutations in one gene.

For example, mutations in the BRCA1 and BRCA2 genes multiply the risk of developing breast and ovarian cancer in women. At the same time, about 20 other genes affect the development of hereditary breast and ovarian cancer. In men, this mutation increases the risk of prostate and breast cancer. In both sexes, the presence of these mutations in cells increases the risk of pancreatic cancer and melanoma.

Many familial forms of cancer develop due to unknown mutations: geneticists have yet to determine them.

Uncertain factors

Today, only some factors that affect carcinogenesis are known. But not all of them.

You can live in an ecologically clean area, carefully monitor your health, be physically active, eat right and still have a risk. This suggests that the development of cancer does not always depend on a person's actions or lifestyle. 

For example, the causes of most somatic mutations that lead to the development of breast or prostate cancer are unknown. Although these types of malignant tumors are among the most common worldwide.

Initially, we wanted to talk about risks, prevention and screening in one article, but we collected so much interesting information that we got three separate materials. Today you learned about the factors that increase the risk. Next time, Atlas will tell you how to manage these factors.

Portal "Eternal youth" http://vechnayamolodost.ru  07.07.2017