2024-02-21 17:17:57 Compiled by Gu Zihuan, editor of Yuanqi.com Whether you know that you or a relative or friend around you has cancer, you may feel stressed and scared. How does cancer exist in the body?
Whether you know that you or a loved one has cancer, it can be stressful and scary. How does cancer start in the body?
What is cancer?
The human body is made up of trillions of cells, and cancer can start almost anywhere and is a disease in which certain cells in the body grow uncontrollably and spread to other parts of the body.
Normally, body cells grow and multiply (through a process called cell division) to form new cells according to the body’s needs. When cells become old or damaged, they die, or undergo apoptosis, and new cells take their place.
Sometimes, though, this orderly process is disrupted, and abnormal or damaged cells grow and multiply when they shouldn’t. These cells may form tumors, which are lumps of tissue. Tumors can be cancerous or noncancerous, or benign.
Cancerous tumors spread to or invade nearby tissue and can spread to distant parts of the body to form new tumors, a process called metastasis. Cancerous tumors may also be called malignant tumors. Many cancers form solid tumors, but blood cancers, such as leukemia, usually do not form solid tumors.
Benign tumors do not spread or invade nearby tissue. Benign tumors usually do not grow back after removal, while cancerous tumors sometimes recur. However, benign tumors can sometimes be quite large. Some can cause severe symptoms or be life-threatening, such as benign tumors in the brain.
Differences between normal cells and cancer cells
1. Normal cells divide and reproduce in a controlled manner, while cancer cells reproduce uncontrollably.
2. Normal cells will die according to the program, while cancer cells will ignore these directions.
3. The normal cells of the organ remain unchanged and all cancer cells are able to move around.
4. Normal cells do not grow as fast as cancer cells.
What causes cancer?
According to the American Institute for Cancer Research, cancer is a hereditary disease, meaning it is caused by changes in genes that control how cells function, especially how they grow and divide.
Normally the body removes cells with damaged DNA before they become cancerous, but the body’s ability to do this decreases as we age, which is part of the reason why the risk of cancer is higher later in life.
Beyond that, each person’s cancer has a unique combination of genetic changes. As the cancer continues to grow, additional changes occur. Even within the same tumor, different cells may have different genetic changes.
While it’s impossible to know exactly why one person develops cancer and another doesn’t, research suggests that certain risk factors may increase a person’s chance of developing cancer, including exposure to chemicals or other substances and certain behaviors. They also include things people have no control over, such as age and family history.
The following are known or suspected risk factors for cancer. Although some of these risk factors can be avoided, others (such as increasing age) cannot. Limiting exposure to avoidable risk factors may reduce the risk of certain cancers.
1.Age
Increasing age is the most important risk factor for cancer overall and for many individual cancer types. The overall incidence of cancer increases steadily with age. However, cancer can be diagnosed at any age, and some cancers, such as bone cancer, are more common in children and teenagers.
2.Alcohol
Drinking alcohol increases the risk of cancers of the mouth, throat, esophagus, larynx, liver and breast. The more you drink, the higher your risk of cancer.
3. Environmental carcinogens
Exposure to toxins in the environment (such as asbestos, pesticides, radon, etc.), plus the amount and duration of exposure and the individual’s genetic background. This can ultimately lead to cancer. In addition, the sun’s ultraviolet radiation can significantly increase the risk of skin cancer, and excessive exposure to radiation therapy may also be a risk factor.
4. Chronic inflammation
Chronic inflammation may be caused by ongoing infections, abnormal immune responses in normal tissues, or conditions such as obesity. Over time, chronic inflammation can cause DNA damage and lead to cancer.
5. Diet and obesity
Eating foods high in fat or sugar may increase the risk of many cancers, and people who are obese may also have an increased risk of several cancers. Conversely, eating a healthy diet, exercising, and maintaining a healthy weight may help reduce the risk of certain cancers.
6. Bacterial and viral infections
Certain infectious agents, including viruses, bacteria, and parasites, may cause cancer or increase the risk of cancer development by affecting cell growth and proliferation, weakening the immune system, or causing chronic inflammation.
7. Smoking
Smoking is the leading cause of cancer and cancer death, and smokers and people who are regularly exposed to secondhand smoke increase the risk of cancers such as lung, pancreatic, esophageal and oral cancer.
Overall, cancer cells develop because of multiple changes in their genes, which have many possible causes, including lifestyle habits, genes inherited from parents, and exposure to environmental factors that may cause cancer. Substances may all play a role. Many times, there may be no obvious reason.
【source】
．National Cancer Institute: What Is Cancer?
．National Cancer Institute: Risk Factors for Cancer
．American Cancer Society: What Is Cancer?
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2024-02-21 09:17:57
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