Cancer is a disease that affects the body’s cells. Normally, the cells grow and multiply to form tissues and organs. But sometimes the cells develop mutations and grow out of control. The resulting masses are called tumors. Cancer can start in many different types of cells and affect almost any part of the body. It may grow quickly and spread to other parts of the body, or it can grow slowly over time. There are more than 100 different kinds of cancer, and each type of cancer has its own set of characteristics.
Cells can become abnormal when certain genes change. These changes (mutations) can affect how the cells grow, divide, and repair themselves. The changes can also affect whether the cell dies when it is supposed to or makes too many new cells. Cancers can grow until they outnumber normal cells, and they can also break apart from the original tumor and travel through the blood or lymph vessels to other parts of the body where they can start forming new tumors. This process is called metastasis.
Each person’s cancer has its own set of genetic changes that cause it to grow and spread. Some of these changes may be inherited, while others can occur as the result of environmental exposures or from errors that happen when cells divide.
Most people get cancer from a combination of factors. These include age, race or ethnicity, gender, family history, and lifestyle choices such as smoking and a diet low in fruits, vegetables, and fiber. Certain chemicals and viruses, such as hepatitis B or HIV, can also increase the risk of getting certain types of cancer.
It is important to note that just because you have one of these factors, it doesn’t mean that you will get cancer. No one knows exactly what causes cancer, and it is never a person’s fault that they get the disease.
When cancer develops, it can cause symptoms that vary widely among people and can be difficult to recognize. Some cancers are easier to treat if they are found early, and this is why it is very important to tell an adult about any unusual or persistent symptoms you are having.
If you’re looking for information about cancer, it is best to stick with sites and resources that are up-to-date and trustworthy. You can find reliable sources by searching online medical journal databases or asking a librarian for guidance. For example, NIH’s page on Evaluating Web Resources for Health Information can help you identify and evaluate resources that are credible.