National Cancer Institute
Science Behind the News Understanding Cancer
Illustration of people thinking about cancer related questions.

What is Cancer?

The term "cancer" refers to a group of diseases in which cells grow and spread unrestrained throughout the body. It is difficult to imagine anyone who has not heard about this disease. Most people have been affected because either a loved one, a friend, or even they themselves are cancer survivors.

It is therefore important for everyone to have a basic understanding about the nature, diagnosis, causes, prevention, and treatment of cancer.

This tutorial will help you find answers to many of your questions about the nature, causes, and prevention of cancer. You may use the program from start to finish or visit sections of particular interest one at a time. Learn about the following topics:

What is cancer?
How is cancer detected and diagnosed?
What causes cancer?
What is the link between genes and cancer?
What is cancer prevention?

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