Cancer is the general class of diseases caused by the body’s own cells reproducing too rapidly. The dividing cells usually create a solid tumor from a mass of body cells, but some types of cancer cause too many cells circulating throughout the body rather than a lump (e.g. leukemia). A tumor needs to be classified as a benign tumor (non-cancerous) versus a malignant tumor (cancerous). A tumor also needs to be distinguished from a variety of other types of lumps (e.g. cysts, abscess, angioma, etc.). Common types of cancer include lung cancer, colon cancer, skin cancer, and many other types of cancer. Diagnosis and treatment of the various types of cancer varies greatly depending on the exact type. General themes of treatment for cancer include chemotherapy (medications), radiotherapy (radiation), surgery (removal of a tumor), and immune therapies.
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Back to: « Cancer
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What is cancer?
Cancer occurs when cells in one part of the body, such as the colon, grow abnormally or out of control. The cancerous cells sometimes spread to other parts of the body, such as the liver. Cancer is the second leading cause of death in the United States.3
How is cancer linked to overweight?
Gaining weight as an adult increases the risk for several cancers, even if the weight gain doesn't result in overweight or obesity. It isn't known exactly how being overweight increases cancer risk. Fat cells may release hormones that affect cell growth, leading to cancer. Also, eating or physical activity habits that may lead to being overweight may also contribute to cancer risk.
How can weight loss help?
Avoiding weight gain may prevent a rise in cancer risk. Healthy eating and physical activity habits may lower cancer risk. Weight loss may also lower your risk, although studies have been inconclusive.
Source: NIDDK (NIH)1
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Cancer arises when cells are unable to repair DNA damage and experience abnormal cell growth and division. The process known as metastasis occurs when cancer cells travel to other parts of the body via the bloodstream and replace normal tissue. According to the American Cancer Society, this chronic disease is the second leading cause of death in the U.S. with half of all men and one-third of all women developing some form of cancer during their lifetimes.
Although cancer is responsible for 23% of all deaths in the U.S., millions of Americans have recovered from the disease. People may reduce their chances of getting cancer by employing prevention methods such as having regular screenings and living a healthy lifestyle.
The NIEHS is committed to understanding the connection between genetics and environmental exposures with regard to cancer. In addition to several Division of Intramural Research (DIR) groups studying the molecular mechanisms behind the disease, the NIEHS funds cancer research at other institutions.
Source: NIEHS (NIH)2
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Cancer occurs when a cell or group of cells begins to multiply more rapidly than normal. As the cancer cells spread, they affect nearby organs and tissues in the body. Eventually, the organs are not able to perform their normal functions. Cancer is the second leading cause of death in the U.S., causing more than 500,000 deaths each year.* Some cancers are caused by substances in the environment: cigarette smoke, asbestos, radiation, natural and man-made chemicals, alcohol, and sunlight. People can reduce their risk of getting cancer by limiting their exposure to these harmful agents.
*Centers for Disease Control and Prevention Office of Minority Health.
Source: NIEHS (NIH)3
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Cancer begins in your cells, which are the building blocks of your body. Normally, your body forms new cells as you need them, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should. These extra cells can form a mass called a tumor. Tumors can be benign or malignant. Benign tumors aren't cancer while malignant ones are. Cells from malignant tumors can invade nearby tissues. They can also break away and spread to other parts of the body.
Cancer is not just one disease but many diseases. There are more than 100 different types of cancer. Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast. The spread of cancer from one part of the body to another is called metastasis. Symptoms and treatment depend on the cancer type and how advanced it is. Most treatment plans may include surgery, radiation and/or chemotherapy. Some may involve hormone therapy, biologic therapy, or stem cell transplantation.
NIH: National Cancer Institute
Source: MedLinePlus (NIH)4
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Cancer is common. Half of all men and a third of women will get a diagnosis of cancer in their lifetime. Many people with cancer do survive. Millions of Americans alive today have a history of cancer.
For most people with cancer, living with the disease is the biggest challenge they have ever faced. It can change your routines, roles and relationships. It can cause money and work problems. The treatment can change the way you feel and look. Learning more about ways you can help yourself may ease some of your concerns. Support from others is important.
All cancer survivors should have follow-up care. Knowing what to expect after cancer treatment can help you and your family make plans, lifestyle changes, and important decisions.
NIH: National Cancer Institute
Source: MedLinePlus (NIH)5
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Cancer. The most common cancers for all women are breast, lung, colon, uterine, and ovarian. Several factors put lesbian and bisexual women at higher risk for developing some cancers. Remember:
- Lesbians are less likely than heterosexual women to have had a full-term pregnancy. Hormones released during pregnancy and breastfeeding are thought to protect women against breast, endometrial, and ovarian cancers.
- Lesbians and bisexual women are less likely to get routine screenings, such as a Pap test, which can prevent or detect cervical cancer. The viruses that cause most cervical cancer can be sexually transmitted between women. Bisexual women, who may be less likely than lesbians to have health insurance, are even more likely to skip these tests.
- Lesbians and bisexual women are less likely than other women to get routine mammograms and clinical breast exams. This may be due to lesbians' and bisexuals' lack of health insurance, fear of discrimination, or bad experiences with health care professionals. Failure to get these tests lowers women's chances of catching cancer early enough for treatments to work.
- Lesbians are more likely to smoke than heterosexual women are, and bisexual women are the most likely to smoke. This increases the risk for lung cancer in all women who have sex with women.
Source: OWH (DHHS)6
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Cancer is a disease in which abnormal cells grow, divide, and spread. In most cancers, these abnormal cells form a mass called a tumor. (Not all tumors are cancer.) Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast. But cancers can spread. They can invade nearby tissues and organs. Or, they can break away and spread to other parts of the body. Symptoms and treatment depend on the cancer type and how advanced it is.
Source: OWH (DHHS)7
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Cancer is the second leading cause of death for women ages 65 or older. Screening tests look for signs of some types of cancer before a woman has symptoms. Cancer is often most treatable when it is found early.
Source: OWH (DHHS)8
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Cancer is a disease in which abnormal cells grow, divide, and spread. In most cancers, these abnormal cells form a mass called a tumor. (Not all tumors are cancer.) Cancers found in the blood or immune system do not form tumors. Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast. But cancers can spread. They can invade nearby tissues and organs. Or, they can break away and spread to other parts of the body. Symptoms and treatment depend on the cancer type and how advanced it is.
Millions of Americans are living with a diagnosis of cancer. But thanks to improved cancer screening and treatment, many people with cancer are able to beat the disease. Still, cancer and cancer treatment can have a big effect on your quality of life, day-to-day activities, work life, and relationships. Pain and fatigue are among the most disabling symptoms. Changes in appearance and abilities both from the cancer and its treatment, as well as feelings such as anger and fear, can affect emotional health. In fact depression affects one-third to one-half of all women diagnosed with cancer.
If you are going through cancer treatment or are a cancer survivor, get the support and medical care you need to take care of your physical and emotional health.
Source: OWH (DHHS)9
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Cancer is a group of many diseases that begin in cells, which are the building blocks of your body. In a person who has cancer, unhealthy cells grow in an out-of-control way. Most cancers are named for the part of the body where they start. You can learn about prostate cancer, which is one of the leading cancer killers of U.S. men, in our section on prostate health. Here we discuss some other cancers that commonly strike men, including skin cancer, lung cancer, colon and rectal cancer, and testicular cancer.
You can lower your risk of getting cancer by adopting a healthy lifestyle. In addition, screenings can help find some cancers early, when they may be most treatable. Ask your doctor which screenings may be right for you.
Source: OWH (DHHS)10
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Cancer and other chronic, noncommunicable diseases (NCDs) are reaching epidemic proportions globally and are taking a particular toll on populations in the developing world. Cancer survival tends to be poorer in developing countries most likely because of a combination of late diagnosis and limited access to treatment. Many cancers could be prevented by applying existing knowledge, implementing tobacco control programs, vaccinating against liver and cervical cancers, providing early detection and treatment, and instituting public health campaigns promoting healthy diets and exercise.
Source: FIC (NIH)11
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Cancer occurs when cell division gets out of control. Usually, the timing of cell division is under strict constraint, involving a network of signals that work together to say when a cell can divide, how often it should happen and how errors can be fixed. Mutations in one or more of the nodes in this network can trigger cancer, be it through exposure to some environmental factor (e.g. tobacco smoke) or because of a genetic predisposition, or both. Usually, several cancer-promoting factors have to add up before a person will develop a malignant growth: with some exceptions, no one risk alone is sufficient.
The predominant mechanisms for the cancers featured here are (i) impairment of a DNA repair pathway (ii) the transformation of a normal gene into an oncogene and (iii) the malfunction of a tumor supressor gene.
Source: NCBI, Genes and Disease (NCBI/NIH)12
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Cancer is a diverse range of diseases where abnormal cells (cells are the basic building blocks of the body) grow rapidly and generally spread throughout the body in an uncontrolled manner. These cancerous cells can invade and destroy surrounding tissue and spread (metastasise) to distant parts of the body.
Source: Queensland Health13
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Cancer is a disease in which abnormal cells grow, divide, and spread. Most cancers are named for where they start. But cancers can spread and invade nearby tissues and organs, or they can break away and spread to other parts of the body. Symptoms and treatment depend on the cancer type and how advanced it is.
Learn about all types of cancer at the National Cancer Institute.
Source: OWH (DHHS)14
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cancer: Cancer, also called malignancy, is a term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems.
Source: Australian Institute of Health and Welfare15
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Cancer is a term used for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. Cancers can develop from most cell types and are distinguished from one another by the location in the body where the disease began (for example, lung) or by the cell type involved (known as histology).
Source: Australian Institute of Health and Welfare16
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cancer (malignant neoplasm): A large range of diseases in which some of the body’s cells become defective, begin to multiply out of control, can invade and damage the area around them, and can also spread to other parts of the body to cause further damage.
Source: Australian Institute of Health and Welfare17
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cancer: Cancer refers to a diverse group of diseases in which some of the body’s cells can become defective, begin to multiply out of control, can invade and damage tissues around them and spread to other parts of the body, causing further damage.
Source: Australian Institute of Health and Welfare18
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Cancer is a condition where cells in a specific part of the body grow and reproduce uncontrollably. The cancerous cells can invade and destroy surrounding healthy tissue, including organs.
Cancer sometimes begins in one part of the body before spreading to other areas. This process is known as metastasis.
Source: NHS Choices UK19
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Cancer: A disease of cellular proliferation that is malignant and primary, characterized by uncontrolled cellular proliferation, local cell invasion and metastasis.20
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Cancer: A tumor composed of atypical neoplastic, often pleomorphic cells that invade other tissues. Malignant neoplasms often metastasize to distant anatomic sites and may recur after excision. The most common malignant neoplasms are carcinomas (adenocarcinomas or squamous cell carcinomas), Hodgkin and non-Hodgkin lymphomas, leukemias, melanomas, and sarcomas.21
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- Source: NIDDK (NIH): niddk.nih.gov/ health-information/ health-topics/ weight-control/ health_risks_being_overweight/ Pages/ health-risks-being-overweight.aspx
- Source: NIEHS (NIH): niehs.nih.gov/ health/ topics/ conditions/ cancer/ index.cfm
- Source: NIEHS (NIH): niehs.nih.gov/ health/ assets/ docs_a_e/ environmental_diseases_environmental_diseases_from_a_to_z_english_508.pdf
- Source: MedLinePlus (NIH): medlineplus.gov/ cancer.html
- Source: MedLinePlus (NIH): medlineplus.gov/ cancerlivingwithcancer.html
- Source: OWH (DHHS): womenshealth.gov/ publications/ our-publications/ fact-sheet/ lesbian-bisexual-health.html
- Source: OWH (DHHS): womenshealth.gov/ cancer/ index.html
- Source: OWH (DHHS): womenshealth.gov/ aging/ diseases-conditions/ cancer.html
- Source: OWH (DHHS): womenshealth.gov/ illnesses-disabilities/ types-illnesses-disabilities/ cancer.html
- Source: OWH (DHHS): womenshealth.gov/ mens-health/ top-health-concerns-for-men/ cancer.html
- Source: FIC (NIH): fic.nih.gov/ ResearchTopics/ Pages/ chronicdiseases-cancer.aspx
- Source: NCBI, Genes and Disease (NCBI/NIH): ncbi.nlm.nih.gov/ books/ NBK22177/
- Source: Queensland Health: conditions.health.qld.gov.au/ HealthCondition/ condition/ 3/ 57/ 634/ urinary-system-cancers
- Source: OWH (DHHS): womenshealth.gov/ cancer
- Source: Australian Institute of Health and Welfare: aihw.gov.au/ reports-statistics/ health-welfare-overview/ australias-health/ glossary
- Source: Australian Institute of Health and Welfare: aihw.gov.au/ reports-statistics/ health-conditions-disability-deaths/ cancer/ about
- Source: Australian Institute of Health and Welfare: aihw.gov.au/ reports-statistics/ health-conditions-disability-deaths/ cancer/ glossary
- Source: Australian Institute of Health and Welfare: aihw.gov.au/ reports-statistics/ population-groups/ older-people/ glossary
- Source: NHS Choices UK: nhs.uk/ conditions/ Cancer/
- Source: Disease Ontology
- Source: Monarch Initiative
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Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.