Learn how potential carcinogens are tested and classified, find lists of known and probable carcinogens, and learn about cancer clusters. Choose a topic to get the facts about these known, possible, and unlikely environmental causes of cancer. For a more complete list and information about how carcinogens are studied and classified, see Known and Probable Human Carcinogens. Cancer A-Z. Read more. Currently, the most significant unpreventable risk factor is age.
According to the American Cancer Society, doctors in the U. Changes in the genes can lead to faulty instructions, and cancer can result. Some genes change proteins that would usually repair damaged cells. This can lead to cancer.
If a parent has these genes, they may pass on the altered instructions to their offspring. Some genetic changes occur after birth, and factors such as smoking and sun exposure can increase the risk. Finally, a person can inherit a predisposition for a type of cancer. A doctor may refer to this as having a hereditary cancer syndrome. Inherited genetic mutations significantly contribute to the development of 5—10 percent of cancer cases. The most common type of cancer in the U.
Each year, more than 40, people in the country receive a diagnosis of one of the following types of cancer:. Other forms are less common.
According to the National Cancer Institute, there are over types of cancer. For example, sarcomas develop in bones or soft tissues, while carcinomas form in cells that cover internal or external surfaces in the body. Basal cell carcinomas develop in the skin, while adenocarcinomas can form in the breast.
Improvements in cancer detection, increased awareness of the risks of smoking, and a drop in tobacco use have all contributed to a year-on-year decrease in the number of cancer diagnoses and deaths. According to the American Cancer Society, the overall cancer death rate declined by 26 percent between and When a person has cancer, the outlook will depend on whether the disease has spread and on its type, severity, and location.
It also prevents them from dying at the natural point in their life cycle. Genetic factors and lifestyle choices, such as smoking, can contribute to the development of the disease.
Several elements affect the ways that DNA communicates with cells and directs their division and death. After nonmelanoma skin cancer, breast cancer is the most common type in the U. However, lung cancer is the leading cause of cancer-related death.
Treatments are constantly improving. It is unknown in these circumstances if the disease is caused by a genetic mutation, exposure to chemicals near a family's residence, a combination of these factors, or simply coincidence.
Some genetic disorders. For example, Wiskott-Aldrich and Beckwith-Wiedemann syndrome are known to alter the immune system. The immune system is a complex system that functions to protect our bodies from infection and disease. The bone marrow produces cells that later mature and function as part of the immune system. One theory suggests that the cells in the bone marrow, the stem cells, become damaged or defective, so when they reproduce to make more cells, they make abnormal cells or cancer cells.
The cause of the defect in the stem cells could be related to an inherited genetic defect or exposure to a virus or toxin. Exposures to certain viruses. Possibly, the virus alters a cell in some way. That cell then reproduces an altered cell and, eventually, these alterations become a cancer cell that reproduces more cancer cells. Environmental exposures. Pesticides, fertilizers, and power lines have been researched for a direct link to childhood cancers. Whether prenatal or infant exposure to these agents causes cancer, or whether it is a coincidence, is unknown.
Some forms of high-dose chemotherapy and radiation. In some cases, children who have been exposed to these agents may develop a second malignancy later in life. A second malignancy is a cancer that appears as a result from treatment of a different cancer. Cancer Genes How do genes affect cancer growth? Types of cancer genes There are three main types of genes that can affect cell growth and are altered mutated in certain types of cancers, including the following: Oncogenes : These genes regulate the normal growth of cells.
Scientists commonly describe oncogenes as similar to a cancer "switch" that most people have in their bodies. What "flips the switch" to make these oncogenes suddenly become unable to control the normal growth of cells and allowing abnormal cancer cells to begin to grow, is unknown. Tumor suppressor genes : These genes are able to recognize abnormal growth and reproduction of damaged cells, or cancer cells, and can interrupt their reproduction until the defect is corrected.
If the tumor suppressor genes are mutated, however, and they do not function properly, tumor growth may occur. Mismatch-repair genes : These genes help recognize errors when DNA is copied to make a new cell. If the DNA does not "match" perfectly, these genes repair the mismatch and correct the error. If these genes are not working properly, however, errors in DNA can be transmitted to new cells, causing them to be damaged. Previous Section Next Section.
Condition Spotlight. Sugar and Health - the Sweet, the Sour, and the Sticky! Play Video How Can I Care for Myself? Clinical Trials Clinical trials are research studies that evaluate a new medical approach, device, drug, or other treatment. Open Trials Closed Trials.
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