What Is Cancer?

Cancer is a group of diseases characterized by the uncontrolled growth and spread of abnormal cells. If the spread is not controlled, it can result in death. Cancer is caused by external factors, such as tobacco, infectious organisms, and an unhealthy diet, and internal factors, such as inherited genetic mutations, hormones, and immune conditions. These factors may act together or in sequence to cause cancer. Ten or more years often pass between exposure to external factors and detectable cancer. Treatments include surgery, radiation, chemotherapy, hormone therapy, immune therapy, and targeted therapy (drugs that specifically interfere with cancer cell growth).

Can Cancer Be Prevented?

A substantial proportion of cancers could be prevented. All cancers caused by cigarette smoking and heavy use of alcohol could be prevented completely. The American Cancer Society estimates that in 2015 almost 171,000 cancer deaths will be caused by tobacco use. The World Cancer Research Fund estimates that about one-quarter to one-third of the new cancer cases expected to occur in the US in 2015 will be related to overweight or obesity, physical inactivity, and poor nutrition, and thus could also be prevented.

Certain cancers are related to infectious agents, such as human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and Helicobacter pylori (H. pylori); many of these cancers could be prevented through behavioral changes, vaccines, or antibiotics.

Many of the more than 3 million skin cancers that are diagnosed annually could be prevented by protecting skin from excessive sun exposure and avoiding indoor tanning.

In addition to preventing cancer through the avoidance of risk factors, regular screening tests that allow the detection and removal of precancerous growths can prevent cancers of the cervix, colon, and rectum.

Early detection of cancer, which usually results in less extensive treatment and better outcomes, can also be achieved through screening for some cancers. Screening is known to reduce mortality for cancers of the breast, colon, rectum, and cervix.

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Incidence & Mortality

How Many People Alive Today Have Ever Had Cancer?

The National Cancer Institute estimates that approximately 14.5 million Americans with a history of cancer were alive on January 1, 2014. Some of these individuals were cancer free, while others still had evidence of cancer and may have been undergoing treatment.

How Many New Cases Are Expected to Occur This Year?

About 1,658,370 new cancer cases are expected to be diagnosed in 2015. This estimate does not include carcinoma in situ (non- invasive cancer) of any site except urinary bladder, and does not include basal cell and squamous cell skin cancers, which are not required to be reported to cancer registries.

How Many People Are Expected to Die of Cancer This Year?

In 2015, about 589,430 Americans are expected to die of cancer, almost 1,620 people per day. Cancer is the second most common cause of death in the US, exceeded only by heart disease, accounting for nearly 1 of every 4 deaths.

What Are the Costs of Cancer?

The Agency for Healthcare Research and Quality (AHRQ) estimates that the direct medical costs (total of all health care expenditures) for cancer in the US in 2011 were $88.7 billion. Half of this cost is for hospital outpatient or office-based provider visits, 35% is inpatient hospital stays, and 11% is prescription medications. These estimates are based on a set of large-scale surveys of individuals and their medical providers called the Medical Expenditure Panel Survey (MEPS), the most complete, nationally representative data on health care use and expenditures. Estimates were accessed directly from the MEPS website ( instead of from the National Heart, Lung, and Blood Institute Fact Book, as in previous years, because an updated fact book was not available.

Lack of health insurance and other barriers prevent many Americans from receiving optimal health care. According to the US Census Bureau, approximately 48 million Americans (15.4%) were uninsured in 2012, including 1 in 3 Hispanics and almost 1 in 10 children (18 years of age or younger). Uninsured patients and those from many ethnic minority groups are substantially more likely to be diagnosed with cancer at a later stage, when treatment is often more extensive, more costly, and less successful. For more information on the relationship between health insurance and cancer, see Cancer Facts & Figures 2008, Special Section, available online at

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Source: American Cancer Society. Cancer Facts & Figures 2015. Atlanta: American Cancer Society; 2015

About Cancer In The U.S.