Cancer: Types, Causes, Prevention, and More
Cancer occurs when genetic mutations in abnormal cells cause them to divide rapidly. You can inherit
mutations or develop them due to environmental factors.
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.
Cancer is one of the leading causes of death in the world. According to the World Health
Organization (WHO)Trusted Source, cancer accounted for almost 1 in 6 deaths in 2020. Experts are
working hard to test out new cancer treatments every day.
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.
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 WHOTrusted Source, 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 80Trusted Source and then diminish, according to the
National Cancer Institute (NCI).
A 2020 reviewTrusted Source suggests this may be the result of:
less effective cell repair mechanisms that come with aging
buildup of risk factors over the course of life
duration of exposures to carcinogens
Some existing health conditions that cause inflammation may also increase your risk of cancer. An
example is ulcerative colitis, a chronic inflammatory bowel disease.
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, a 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 a 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.
Learn more about specific types of cancer with the resources below.
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
