Thanh Kieu Doctor

From Cancer Guidelines Wiki

Causes of cancer

Cancer develops when there are changes to the DNA (mutations) in a cell that allow it to grow out of control. Cancer cells can then crowd out normal cells or invade body tissues. Radiation, carcinogens, infections, and your genetic makeup can increase your risk of mutations that lead to cancer.

Most people don't realize that cancer is preventable in many cases. Understanding cancer causes and risk factors is the first step in cancer prevention.

Common causes

According to the American Cancer Society and Cancer Institute, the most common causes and risk factors for cancer are:

• Smoking and tobacco use

• Alcohol

• Lack of physical activity

• Overweight or obese

• Diet

• Exposure to the sun

• Exposure to radiation

• Viral and other infections

• Exposure to carcinogens

• Family history and genetics

• Chronic inflammation

• Hormonal

• Immunosuppressive

• Year old

Exposure to the Environment

Your surroundings can increase your risk of developing cancer. Carcinogens — substances and exposures that can lead to cancer — can be found in homes, workplaces, and outdoors. Tobacco use and smoking fall into this category.

Another example is exposure to asbestos, a group of minerals found in some older homes and industrial building materials that can cause mesothelioma, a type of cancer of the lining of the lungs. People exposed to high amounts of benzene (found in gasoline, cigarette smoke, pollution) have an increased risk of cancer.

There are many other substances in the environment that can be dangerous to you. Be careful with chemicals in your home and always take time at work to read the information provided about the chemicals you work with.  Content prepared based on:

Exposure to radiation

The most common form of radiation exposure is from the sun. Another environmental exposure is radon gas, which can be present in soil and can build up in your home. You may also be exposed due to imaging or medical treatment.


Infections can increase cancer risk in a number of ways. Some viral infections directly affect DNA to produce cancerous changes. Other infections can lead to long-term inflammation, increasing the risk of disease. Other infections, such as HIV, suppress the immune system, so it cannot effectively protect against cancer growth.

Human papillomavirus - HPV increases the risk of cancers of the cervix, anus, vulva, and vagina. Studies suggest that the papilloma virus also plays an important role in many head and neck cancers, and ongoing research is looking at its possible role in other cancers. The papillomavirus vaccine is recommended for girls and boys starting at age 11 or 12.

Year old

Although cancer can occur at any age, the average age for a cancer diagnosis is between 65 and 74, depending on the type.

Over the years, you've been exposed to more carcinogens and inflammatory processes, and more time for slow-growing cancers to become symptomatic. Your body also becomes less efficient at finding and destroying cancerous and precancerous cells.

That said, there are some forms of cancer that are more common in children, including bone cancer and some forms of leukemia.


Genes are the ultimate cause of all cancers, but in most cases these are acquired mutations that are not passed on to your children. You have "healthy" genes, but a mutation occurs in a cell and can then grow out of control. There is often a latent susceptibility to cancer due to inactivation of oncogenes and tumor suppressor genes.

But in 5% to 10% of cases, cancer is caused by a family cancer syndrome that can be inherited. If you have a family history of cancer, such as breast cancer, it's important to take additional precautions. Genetic tests are available for some inherited cancers.

Note: Remember that if you have a family history of cancer, it does not mean you will develop it. You just have a greater chance of developing it (a genetic predisposition).

Lifestyle risk factors

Many of the main risk factors for cancer are ones that you can control. This can be especially empowering for those who are aware of certain tendencies.


Smoking not only affects the lungs but also increases the risk of many cancers. In fact, smoking causes 30% of all cancer deaths in the United States and is responsible for 80% of lung cancer deaths.

Quitting smoking immediately reduces the risk of cancer.


Alcohol is a stimulant that can damage cells and promote the production of cancer-causing chemicals in the colon. To reduce the risk of cancer from alcohol, the American Cancer Society recommends limiting alcohol to one drink per day for women and two drinks per day for men.

Lack of physical activity

Exercising for at least 30 minutes a day, five days a week significantly reduces the risk of cancer. You don't have to run a marathon. It has been found that even light exercise - such as working in the garden a few days a week - reduces the risk of lung cancer, among other types.


Obesity is a leading cause of cancer. It increases the risk of breast cancer, colon and rectal cancer, endometrial cancer, esophageal cancer, pancreatic cancer, and kidney cancer, among others.

Reaching or maintaining a healthy body weight can reduce your risks.


A diet that focuses on plants, including vegetables, fruits, whole grains, and protein from peas and beans is best for reducing cancer risk. Processed meats, red meat, sugary drinks and refined carbohydrates should be limited.


Skin cancer can be caused by overexposure to UV rays from the sun. Sunburn - even a tan - is actually the result of sun-damaged skin.

Many cases of skin cancer can be prevented through a little planning. Wearing sunscreen can help, but you should also be exposed to the sun safely. Avoid direct mid-day sunlight (between 10am and 2pm), sit under an umbrella, wear protective clothing, and don't forget to wear sunglasses to protect your eyes. One form of skin cancer - melanoma - tends to affect the eyes.

Unsafe sex

Having unprotected sex can increase your risk of contracting the papillomavirus, HIV, and hepatitis B, all of which increase the risk of cancer.

Questions for you

• What causes cancerous tumors to form and grow?

Tumors form when cells in the body normally die to make room for new cells that instead grow out of control. This happens due to genetic changes, or mutations, in the cell. The proliferation of the growing cells may be benign, meaning it will not extend beyond the area in which it formed, or it may be malignant and have the potential to metastasize or spread to other organs. other part of the body.

• How does cancer spread?

Cancer can spread by growing into surrounding tissues. It can also metastasize: Malignant cells can break away from the original tumor and then be carried to other parts of the body through the bloodstream or the lymphatic system.

• Do I have to have a certain gene to get cancer?

No. Only 5% to 20% of cancers are caused by inherited genetic mutations, known as germline mutations. Such mutations can be passed on from generation to generation. That said, it is important to know that just because you inherit a cancer gene, it does not mean that you will definitely develop cancer.

• Can healthy people get cancer?

Yes. You can develop cancer even if you don't inherit a genetic predisposition for the disease and you pass every health check and screening with flying colors. There are still risk factors for cancer that you may not be aware of or have previously been exposed to, such as air pollution, secondhand smoke, UV exposure, and more. That said, it's never too late to take steps to reduce your cancer risk.


Rates of new cancer diagnoses are declining in the United States, but more than 1.7 million people will be diagnosed with cancer each year. However, due to early detection and better treatment, cancer mortality has decreased by 27% over 25 years and continues to decrease by 1.8% each year. While you can't avoid all causes of cancer, you can significantly reduce your risk by making lifestyle changes. These measures also reduce the risk of other major diseases. Related pages: