{"id":772,"date":"2020-07-22T18:43:02","date_gmt":"2020-07-22T18:43:02","guid":{"rendered":"http:\/\/opentextbooks.concordia.ca\/fundamentalsofhealthandphysicalactivity\/?post_type=chapter&p=772"},"modified":"2021-07-19T15:17:20","modified_gmt":"2021-07-19T15:17:20","slug":"2-8-1-what-is-cancer","status":"publish","type":"chapter","link":"https:\/\/opentextbooks.concordia.ca\/fundamentalsofhealthandphysicalactivity\/chapter\/2-8-1-what-is-cancer\/","title":{"raw":"2.8.1. What is Cancer?","rendered":"2.8.1. What is Cancer?"},"content":{"raw":"

What Is Cancer?<\/h1>\r\nCancer\u00a0is the name given to a collection of related diseases in which the body\u2019s cells begin to divide without stopping and spread into surrounding tissues.\r\n\r\nMany cancers form solid tumors, which are masses of tissue. Cancers of the blood, such as leukemias, generally do not form solid tumors.\r\n\r\nCancerous tumors are [pb_glossary id=\"487\"]malignant[\/pb_glossary], which means they can spread into, or invade,\u00a0nearby tissues. In addition, as these tumors grow, some cancer cells can break off and travel to distant places in the body through the blood or the lymph system and form new tumors far from the original tumour. Each person\u2019s cancer has a unique combination of genetic changes. As the cancer continues to grow, additional changes will occur. Even within the same tumor, different cells may have different genetic changes.\r\n
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\r\n\r\nUnlike malignant tumors, [pb_glossary id=\"488\"]benign[\/pb_glossary] tumors do not invade nearby tissues. However, some benign tumors can be quite large. When removed, they usually do not grow back, whereas malignant tumors sometimes do. Unlike most benign tumors elsewhere in the body, benign tumors in the brain can be life threatening.\r\n\r\nMore than one hundred diseases are classified as different forms of cancer, all of them characterized by the uncontrolled growth of abnormal cells.\u00a0<\/b>Cancer is triggered by mutations in a cell\u2019s genetic material. The cause of these changes may be inherited, or it may result from exposure to carcinogens, which are agents that can cause cancer. Carcinogens include chemicals, viruses, certain medical treatments such as radiation, pollution, or other substances and exposures that are known or suspected to cause cancer.[footnote]Known and Probable Human Carcinogens. American Cancer Society.http:\/\/www.cancer.org\/Cancer\/CancerCauses\/OtherCarcinogens\/GeneralInformationaboutCarcinogens\/known-and-probable -human-carcinogens. Updated November 3, 2016. Accessed April 15, 2018.[\/footnote] The National Institutes of Health has classified fifty-four different compounds as known cancer-causing agents in humans.[footnote]Israel B. How Many Cancers Are Caused by the Environment?. https:\/\/www.scientificamerican.com\/article\/how-many-cancers-are-caused-by-the-environment. Published May 10, 2010. Accessed April 15, 2018.[\/footnote]\r\n\r\nUnder normal conditions, a healthy cell will either repair any damage that has been done or self destruct so that no future cells will be affected. Cells become cancerous when their DNA is damaged, but they do not self-destruct or stop reproducing as normal cells would. As these abnormal cells continue their rapid growth, in most cancers they coalesce in a mass called a tumor. Cancer cells can overwhelm healthy cells and interfere with the healthy functioning of the body. They can also invade other organs and spread throughout the body in a process known as metastasis. Scientists and the medical community are giving considerable attention to the early stages of cancer, from the moment a healthy cell is exposed to a carcinogen to the point where cells with damaged DNA are replicating out of control. Intervention at any of these early stages could prove to be quite beneficial, because it is thought that most cancers are the result of lifestyle choices and environmental exposure.\r\n\r\nThe risk factors for different cancers can vary. For example, exposure to ultraviolet radiation from the sun and from tanning beds is a risk factor for skin cancer, while exposure to asbestos is a risk factor for mesothelioma cancer. Table 2.8.1.1 \u201cThe Risk Factors for Cancer\u201d shows some common risk factors for a number of different types of cancer.\r\n
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Table 2.8.1.1<\/b> The Risk Factors for Cancer <\/em><\/p>\r\n\r\n\r\n\r\n\r\n\r\n
Unmodifiable Risk Factors<\/strong><\/td>\r\nModifiable Risk Factors<\/strong><\/td>\r\n<\/tr>\r\n
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  • Age:<\/strong>\u00a0Most cancers occur in people over the age of sixty-five. However, people of all ages, including children, can get cancer.<\/li>\r\n \t
  • Family history:<\/strong>\u00a0Certain types of cancer have a genetic link. However, environmental factors may also play a part.<\/li>\r\n<\/ul>\r\n<\/td>\r\n
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