Cancer
A group of diseases involving uncontrolled cell growth and potential spread.
Cancer isn't one disease but a large family of them, all marked by cells growing out of control. This often creates tumors, and when those tumors are malignant, they can invade nearby tissue or travel to other parts of the body. Benign tumors, by contrast, stay put. There are more than 100 different kinds that can affect people. The name itself goes back to ancient Greek—*karkinos* means both "crab" and "tumor"—and English picked it up in the medical sense around 1600.
Roughly a third of cancer deaths are linked to tobacco, alcohol, obesity, a diet low in fruits and vegetables, and lack of exercise. Other triggers include certain infections, ionizing radiation, and environmental pollutants. Infections from specific viruses, bacteria, and parasites cause about 16 to 18 percent of cancers worldwide. The culprits include *Helicobacter pylori*, hepatitis B, hepatitis C, and HPV. HIV doesn't directly cause cancer, but it weakens the immune system, which can raise the risk of cancer from other infections—sometimes by thousands of times. Vaccines for hepatitis B and HPV have been shown to nearly wipe out the cancers those viruses cause.
These outside factors work, at least in part, by altering a cell's genes. Usually, many genetic changes have to pile up before cancer develops. Only about 5 to 10 percent of cancers come from inherited genetic defects. Cancer can be spotted through certain signs, symptoms, or screening tests, then investigated with medical imaging and confirmed with a biopsy.
You can lower your risk by not smoking, keeping a healthy weight, limiting alcohol, eating plenty of vegetables, fruits, and whole grains, getting vaccinated against certain infections, cutting back on processed and red meat, and avoiding too much direct sun. Early screening helps for cervical and colorectal cancer, though the benefits for breast cancer screening are debated. Treatment often combines radiation, surgery, chemotherapy, and targeted drugs. Newer, more personalized approaches that harness the immune system—cancer immunotherapy—are emerging. Palliative care, which focuses on pain and symptom management, is especially important for advanced disease. Survival odds depend on the cancer type and how far it has spread when treatment starts. In developed countries, children under 15 diagnosed with cancer have an average five-year survival rate of 80%. For all ages in t
- types
- Over 100
- global_cases_2015
- 90.5 million
- annual_cases_2019
- 23.6 million
- annual_deaths_2019
- 10 million
- five_year_survival_US_all_ages
- 66%
- five_year_survival_children_under_15_dev
- 80%
- economic_cost_2010
- US$1.16 trillion
Lore & Background
Cancer comprises a large family of diseases that involve abnormal cell growth with the potential to invade or spread to other parts of the body, forming a subset of neoplasms. All tumor cells show six hallmarks of cancer: cell growth and division absent proper signals, continuous growth despite contrary signals, avoidance of programmed cell death, limitless cell divisions, promoting blood vessel construction, and invasion of tissue with formation of metastases. The progression from normal cells to a detectable mass to cancer involves multiple steps known as malignant progression.
Reader's Guide
Cancer is a major global health burden, with about 90.5 million people worldwide having cancer in 2015 and 10 million deaths in 2019. Approximately 90–95% of cases are due to environmental and lifestyle factors, including tobacco use (25–30%), diet and obesity (30–35%), infections (15–20%), and radiation (up to 10%). The remaining 5–10% are due to inherited genetic defects. Prevention strategies include not smoking, maintaining a healthy weight, limiting alcohol, eating vegetables and fruits, vaccination against hepatitis B and HPV, and limiting processed meat and sun exposure. Early detection through screening is useful for cervical and colorectal cancer, though benefits for breast cancer are controversial. Treatment often combines radiation therapy, surgery, chemotherapy, and targeted therapy, with emerging personalized immunotherapies. Palliative care is important for advanced disease. Survival depends on cancer type and stage at diagnosis; in children under 15 in the developed world, the five-year survival rate averages 80%, while in the US for all ages it is 66%.
Did You Know?
- About 33% of deaths from cancer are caused by tobacco, alcohol, obesity, lack of fruit and vegetables, and lack of exercise.
- Infection with specific viruses, bacteria, and parasites causes approximately 16–18% of cancers worldwide.
- Vaccination against hepatitis B virus and human papillomavirus has been shown to nearly eliminate the risk of cancers caused by these viruses.
- The risk of suicide in people with cancer is approximately double.
More in Surgery & Trauma 1-24
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record