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Learn About Cancer Basics©
Written by Cancer Center Staff

Source: Cancer Resource Room

What is Cancer? Common Questions
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What Is Cancer?
Cancer is a disease caused by cells that grow without the body's control. These uncontrolled cells grow to form a tumor. The cancer cells can break away from the tumor and spread to other parts of the body. Cancer cells do not work like normal cells. Whatever job the normal cells are supposed to do in the body is not done correctly or at all by cancer cells.

Each type of cancer depends on the cells that are the cause of the disease. For example, if the abnormal, cancer-causing cells are lung cells, then the cancer is lung cancer. Any organ or tissue can develop cancer and the cancer will be named for that organ. Cancer cells from the breast cause breast cancer; cancer cells in the pancreas cause pancreatic cancer, and so on.

Are all cancers the same?
No two cancers are exactly the same, even when they are cancers of the same organ. The differences have to do with what is called the "biology" of the disease. While there are general ways in which cancers are similar, it means that each cancer has its own characteristics that make each person react differently to the cancer and its treatment. Cancer is a change in cells that lets the cells divide into new cells without any control. As new cells are produced, a tumor is formed. In cancers, the cells can break free of the tumor or group of cancer cells and travel through the blood or lymph system (the infection fighting system) to other parts of the body.

The tendency of cancer cells to grow, divide into more cancer cells, and spread through the blood or lymph varies among cancers. These differences in growth and spread of a cancer have a lot to do with how each one is treated. Cancers that grow slowly and do not spread easily often can be treated by simply removing the tumor. Other cancers that tend to grow rapidly and spread easily will need treatment of the original tumor and of the whole body. These treatments often include surgery and chemotherapy.

Do cancers come from something inside or outside the body?
Cancer is a disease that is caused by the body's own cells. Our cells have special control signals in them that are supposed to limit the size of cells and the number of new cells. These controls limit cells to just what the body needs. In cancer cells, the control signals are lost and the cells grow when they should not. No one knows why these controls fail, but it is not a problem that can be "caught" like a cold or other infection.

There are some cancers that have been linked to things in the environment. Even though it still is not known exactly how these conditions cause the cancer to start, the association is strong enough to warn people to avoid them.

Some examples will help in understanding this:

  • UV radiation in sunlight causes changes in skin cells that can lead to melanoma, a serious skin cancer.
  • Sun exposure is also linked to two other cancers, squamous cell carcinoma of the skin and basal cell carcinoma.
  • Knowing about this link between sun exposure and skin cancers has lead to the widespread use of sunblock lotions.
  • Another example of a link between cancer and an environmental cause is smoking and lung cancer.

Many of these examples exist, and they help us avoid things that make the risk of getting cancer higher than normal.

What do the names of cancers mean?
Cancers are named in several different ways. This can be confusing.

Cancers may be named for the organ the cancer started in.

  • Most cancers are named for the organ the cancer cells are part of.
  • For example, lung cancers start from lung cells. There are different types of lung cells, so there are several types of lung cancers.
  • Cancer cells from the breast cause breast cancer; cancer cells in the pancreas cause pancreatic cancer, and so on.

Cancers may be named for the type of cell that is cancerous in the organ.

  • In the breast, there are cells that produce milk in the lobules. If these cells become cancerous, they cause lobular cancer of the breast. But if the cells of the tubes or ducts that deliver the milk to the nipple cause cancer, it is called ductal cancer of the breast.
  • The name usually describes the type of cell and the organ where the cancer started.
  • When a cancer spreads from where it started to another part of the body, it keeps the same cancer name. If cancer starts in the prostate, it is prostate cancer. If it spreads to the bone, it is still prostate cancer. If it spreads to the lungs or liver, it is still prostate cancer. The only thing that changes is that when a cancer spreads, it is called "metastatic." So, metastatic prostate cancer of bone is cancer that started in the prostate and spread to the bones. It is not bone cancer.

Cancers also may have names that do not have anything to do with where the disease started. Sometimes cancers are named for the physician who first described it.

  • For example, Hodgkin's disease is named for the doctor who described the disease.

Other cancers are named for the type of cell the cancer cells resemble.

  • An example of this is synovial cell sarcoma, which does not start in the tissue called synovium, but the cells look like synovial cells.

These names are not meant to be confusing. They let the doctors who treat cancer communicate about these different diseases accurately, especially when choosing treatments and following the success of the treatments. If you do not understand what the name of a cancer means, it is helpful to ask your doctor to explain it.

A word about words
When you get cancer, many things can be unfamiliar. One difficulty is trying to understand a lot of new words, or new uses of words we think we know. The following words are explained to help with this problem. Many other words are explained in the Learn About Cancer sections where they apply to a certain cancer.

  • Local disease-means the cancer located in the spot it started
  • Distant disease-is cancer that has spread from the place it started to other parts of the body, that is, "distant" from the original spot
  • Regional nodes-lymph nodes nearby the original site of the cancer. If the cancer spreads, it usually goes to these lymph nodes before spreading further.
  • Distant nodes-lymph nodes not near the original site of the cancer
  • Primary-the original cancer, the place the cancer started, or the organ the cancer cells first came from
  • Second primary-a new cancer in a person who has had a different type of cancer in the past. It means the new cancer is not a return or spread of the first cancer, but is a separate disease altogether.
  • Recurrent disease-cancer that has returned or regrown after the original treatment was completed
  • Metastatic-spread of cancer from the place it started to other parts of the body. Common places for cancer to metastasize are lymph nodes, bones, liver, lung, and brain.
  • Margin-the edge of tissue that is removed with a tumor. It is what separates the tumor tissue from the surrounding normal tissues. If the margin is "negative," then no tumor cells are at the edge of what was removed. If the margin is "positive," then there are tumor cells at the edge of what was removed. Margins are often measured in millimeters (mm) to describe how far the tumor cells are from the normal tissue it was cut away from.
  • Positive-what was being looked for was found or is there.
  • Negative-what was being looked for was not found
  • Carcinoma-cancer

What's New
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Support & Education Programs

We know that being diagnosed with cancer can be stressful for you and your family. We offer a variety of cancer support services to help patients and families gain the support and information they will need to meet the challenges ahead.

We offer several support, educational, and wellness programs such as "Cancer-Related Fatigue...What You Should Know " and "Coping with Cancer Pain" and many others. Look for the current offerings in the HOPES calendar.