Cancer is a large group of diseases that occur when abnormal cells divide rapidly and can spread to other tissue and organs.
These rapidly growing cells may cause tumors. They may also disrupt the body’s regular function.
What causes cancer?
The main cause of cancer is mutations or changes to the DNA in your cells. Genetic mutations can be inherited. They can also occur after birth as a result of environmental forces.
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These external causes, called carcinogens, can include:
physical carcinogens like radiation and ultraviolet (UV) light
chemical carcinogens like cigarette smoke, asbestos, alcohol, air pollution, and contaminated food and drinking water
biological carcinogens like viruses, bacteria, and parasites
According to the WHO, about 33 percent of cancer deaths may be caused by tobacco, alcohol, high body mass index (BMI), low fruit and vegetable consumption, and not getting enough physical activity.
Risk factors
Certain risk factors may increase your chance of developing cancer. These risk factors can include:
- tobacco use
- high alcohol consumption
- an unhealthy diet, characterized by red and processed meat, sugary drinks and salty snacks, starchy foods, and refined carbohydrates including sugars and processed grains, according to a 2017 review
- a lack of physical activity
- exposure to air pollution
- exposure to radiation
- unprotected exposure to UV light, such as sunlight
- infection by certain viruses including H. pylori, human papillomavirus (HPV), hepatitis B, hepatitis C, HIV, and the Epstein-Barr virus, which causes infectious mononucleosis
The risk of developing cancer also increases with age. In general, the risk of developing cancer appears to increase until the age of 70 to 80 and then diminish, according to the National Cancer Institute (NCI).
Types of cancer
Cancers are named for the area in which they begin and the type of cell they are made of, even if they spread to other parts of the body. For example, cancer that begins in the lungs and spreads to the liver is still called lung cancer.
There are also several clinical terms used for certain general types of cancer:
- Carcinoma is cancer that starts in the skin or the tissues that line other organs.
- Sarcoma is a cancer of connective tissues such as bones, muscles, cartilage, and blood vessels.
- Leukemia is a cancer of the bone marrow, which creates blood cells.
- Lymphoma and myeloma are cancers of the immune system.
Other specific types of cancer are as follows:
- appendix cancer
- bladder cancer
- bone cancer
- brain cancer
- breast cancer
- cervical cancer
- colon or colorectal cancer
- duodenal cancer
- ear cancer
- endometrial cancer
- esophageal cancer
- heart cancer
- gallbladder cancer
- kidney or renal cancer
- laryngeal cancer
- leukemia
- lip cancer
- liver cancer
- lung cancer
- lymphoma
- mesothelioma
- myeloma
- oral cancers
- ovarian cancer
- pancreatic cancer
- penile cancer
- prostate cancer
- rectal cancer
- skin cancer
- small intestine cancer
- spleen cancer
- stomach or gastric cancer
- testicular cancer
- thyroid cancer
- uterine cancer
- vaginal cancer
- vulvar cancer
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The importance of early detection
Early detection is when cancer is found in its early stages. This can increase the effectiveness of treatment and lower the mortality rate.
Cancer screenings may help detect signs of cancer early. Some common cancer screenings may detect:
- Cervical cancer and prostate cancer. Some screenings, such as for cervical cancer and prostate cancer, may be done as part of routine exams.
- Lung cancer. Screenings for lung cancer may be performed regularly for those who have certain risk factors.
- Skin cancer. Skin cancer screenings may be performed by a dermatologist if you have skin concerns or are at risk of skin cancer.
- Colorectal cancer. The American Cancer Society (ACS)Trusted Source recommends regular screenings for colorectal cancer beginning at age 45. These screenings are typically performed during a colonoscopy. At-home testing kits may also be able to detect some forms of colorectal cancer, according to a 2017 review of researchTrusted Source.
- Breast cancer. Mammograms to test for breast cancer are recommended for women ages 45 and older trusted Source, but you may choose to begin screenings at age 40. In people at high risk, screenings may be recommended earlier.
If you have a family history of cancer or have a high risk of developing cancer, it is important to follow a doctor’s screening recommendations.
Signs and symptoms of cancer can include:
- lumps or growths on the body
- unexplained weight loss
- fever
- tiredness and fatigue
- pain
- night sweats
- changes in digestion
- changes in skin
- cough
Specific types of cancers often have their own warning signs. If you are experiencing unexplainable symptoms, it is best to contact a doctor for a diagnosis.
