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Cancer 101

Two female doctors study a mammogram

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What is cancer?

Cancer is a large group of diseases with one thing in common: they all happen when the body’s normal cells become abnormal cells that multiply and spread to other parts of the body.

How does cancer develop?

Cancer starts when our cells divide uncontrollably and spread into surrounding tissues. As the cancer cells grow out of control, they can crowd out normal cells.

Cancer can develop anywhere in the body and is named for the part of the body where it started. For example, colon cancer that starts in the colon is still called colon cancer even if it spreads (metastasizes) to other parts of the body. There are many types of cancer.

The 2 Main categories of cancer are:

  • Hematologic (blood) cancers are cancers of the blood cells, including leukemia, lymphoma, and multiple myeloma.
  • Solid tumor cancers are cancers of any of the other body organs or tissues. The most common solid tumors are breast, prostate, lung, and colorectal cancers.

What is a tumor?

A tumor is a lump or growth. Some lumps are cancer, but many are not.

  • Benign tumor: a lump that is not cancer. These do not spread to other parts of the body.
  • Malignant tumor: a lump that is cancer. These can spread to other parts of the body. See below for more information on how cancer spreads.

What is the cancer stage?

According to the American Society of Clinical Oncology (ASCO), "Stage" is one way to measure cancer. Doctors give many types of cancer a number from 1 to 4; this is called the stage number. It is based on many factors, such as where the cancer is in the body, how big it is, if it has spread and by how much, and if there is more than one tumor.

A lower stage (such as stage 1 or 2) means that the cancer has not spread very much. A higher number (such as a stage 3 or 4) means it has spread more. The stage of the cancer is very important in choosing the best treatment for a person. Ask your doctor about your cancer's stage and what it means for you. More information about the stages of cancer can be found on the American Society of Cancer page: cancer's stage.

How does cancer spread?

Cancer can spread from where it started (the primary site) through the bloodstream or lymph system to other parts of the body and begin forming new tumors. When cancer spreads to a new part of the body it is called metastasis.

"When cancer cells break away from a tumor, they can travel to other areas of the body through either the bloodstream or the lymph system. Cancer cells that travel through the bloodstream may reach distant organs. If they travel through the lymph system, the cancer cells may end up in lymph nodes. Either way, most of the escaped cancer cells die or are killed before they can start growing somewhere else. But one or two might settle in a new area, begin to grow, and form new tumors. This spread of cancer to a new part of the body is called metastasis.

Cells that make up a metastasis are the same type of cells as in the primary cancer. They are not a new type of cancer. For instance, breast cancer cells that spread to the lungs are still breast cancer and NOT lung cancer. And colon cancer cells that spread to the liver are still colon cancer. "

-Anne Schott, M.D., from the article Understanding Cancer Recurrence.

How is cancer treated?

Many procedures and medications are available to treat cancer. Treatments like surgery and a high-energy treatment called radiation therapy are used to treat a specific tumor or area of the body. Drug treatments (such as chemotherapy, immunotherapy, or targeted therapy) are often called "systemic" treatments because they can affect the entire body. You might be offered a combination of surgery, radiation therapy, and medications. To learn about the most common types of treatments for cancer please click on the American Society of Cancer ( links below:

How can I cope with having cancer?

Staying organized and getting support are important. You can use a notebook, file folder, or mobile app to keep health information in one place and share it with people involved in your care. This is especially important when you are upset, confused, or not feeling well.

Ask to speak to a counselor, social worker, patient navigator, or another health care professional to get answers to questions about insurance and finances, emotional support, and help with daily activities. Getting support will help you and your loved ones cope with the diagnosis and treatment. Find more information at

Can I prevent cancer?

You can engage in all the right health behaviors and still be diagnosed with cancer. However, there are still several steps you can take to help prevent a cancer diagnosis or ensure that if you are diagnosed with cancer you are diagnosed at an earlier stage.

To learn more about the risk factors and screening please visit our Rogel Cancer Center Cancer Prevention Screening page or visit our Cancer 101 Resource Library to access external resources.

  1. Understanding the Risk Factors—There are several key behavioral risk factors such as diet & exercise, limiting alcohol consumption, and avoiding tobacco use that all play a role in helping to prevent cancer.
  2. Diet & Exercise—One third of all cancer deaths in the United States each year are linked to diet and physical activity including being overweight or obese.
  3. Alcohol Consumption—Alcohol consumption can lead to several different cancers, including liver cancer. According to the American Cancer Society, on a day when you are drinking alcohol, people should limit their intake to no more than 2 drinks per day for men and 1 drink per day for women.
  4. Tobacco—Smoking tobacco cigarettes or using chewing tobacco is responsible for almost 30 percent of all cancer diagnoses.
  5. Screening—Speaking with your physician about regularly screening for screen able cancers is another controllable form of prevention. Screening allows us and our physicians to monitor our bodies on an annual basis.