+ -Text Size

What is cancer?
A guide for patients and families

What is cancer?

Cancer can start any place in the body. It starts when cells grow out of control and crowd out normal cells. This makes it hard for the body to work the way it should.

Cancer can be treated very well for many people. In fact, more people than ever before lead full lives after cancer treatment.

Here we will explain what cancer is and how it’s treated. You’ll find a list of words about cancer and what they mean at the end of this booklet.

Cancer basics

Cancer is not just one disease.

There are many types of cancer. It’s not just one disease. Cancer can start in the lungs, the breast, the colon, or even in the blood. Cancers are alike in some ways, but they are different in the ways they grow and spread.

How are cancers alike?

The cells in our bodies all have certain jobs to do. Normal cells divide in an orderly way. They die when they are worn out or damaged, and new cells take their place. Cancer is when the cells start to grow out of control. The cancer cells keep on growing and making new cells. They crowd out normal cells. This causes problems in the part of the body where the cancer started.

Cancer cells can also spread to other parts of the body. For instance, cancer cells in the lung can travel to the bones and grow there. When cancer cells spread, it’s called metastasis (meh-TAS-tuh-sis). When lung cancer spreads to the bones, it’s still called lung cancer. To doctors, the cancer cells in the bones look just like the ones from the lung. It’s not called bone cancer unless it started in the bones.

How are cancers different?

Some cancers grow and spread fast. Others grow more slowly. They also respond to treatment in different ways. Some types of cancer are best treated with surgery; others respond better to drugs called chemotherapy (key-mo-THER-uh-pee). Often 2 or more treatments are used to get the best results.

When someone has cancer, the doctor will want to find out what kind of cancer it is. People with cancer need treatment that works for their type of cancer.

What are tumors?

Most cancers form a lump called a tumor or a growth. But not all lumps are cancer. Doctors take out a piece of the lump and look at it to find out if it’s cancer. Lumps that are not cancer are called benign (be-NINE). Lumps that are cancer are called malignant (muh-LIG-nunt).

There are some cancers, like leukemia (cancer of the blood), that don’t form tumors. They grow in the blood cells or other cells of the body.

    “There is a fear that goes through you when you’re told you have cancer. It’s so hard in the beginning to think about anything but your diagnosis. It’s the first thing you think about every morning. I want people with cancer to know it does get better. Talking about your cancer helps you deal with all of the new emotions you are feeling. Remember, it’s normal to get upset.”

– Delores, cancer survivor

What stage is the cancer?

The doctor also needs to know if and how far the cancer has spread from where it started. This is called the cancer stage. You may have heard other people say that their cancer was stage 1 or stage 2. Knowing the stage of the cancer helps the doctor decide what type of treatment is best.

For each type of cancer there are tests that can be done to figure out the stage of the cancer. As a rule, a lower stage (such as a 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. Stage 4 is the highest stage.

Ask your doctor to explain the stage of your cancer and what it means for you.

How is cancer treated?

The most common treatments for cancer are surgery, chemotherapy, and radiation (ray-dee-A- shun).

Surgery can be used to take out the cancer. The doctor might also take out some or all of the body part the cancer affects. For breast cancer, part (or all) of the breast might be removed. For prostate cancer, the prostate gland might be taken out. Surgery is not used for all types of cancer. For example, blood cancers like leukemia are best treated with drugs.

Chemo (short for chemotherapy) is the use of drugs to kill cancer cells or slow their growth. Some chemo can be given by IV (into a vein through a needle), and others are a pill you swallow. Because chemo drugs travel to nearly all parts of the body, they are useful for cancer that has spread.

Radiation is also used to kill or slow the growth of cancer cells. It can be used alone or with surgery or chemo. Radiation treatment is like getting an x-ray. Sometimes it’s given by putting a “seed” inside the cancer to give off the radiation.

    “What was helpful for me was taking the time to step back and see the big picture. Getting the answers to my questions helped me to make a good decision. I did what I wanted and needed to do. I did things that made me feel comfortable, not what others thought I needed to do to be comfortable.”

    – Kevin, cancer survivor

What treatment is best for me?

Your cancer treatment will depend on what’s best for you. Some cancers respond better to surgery; others respond better to chemo or radiation. Knowing the type of cancer you have is the first step toward knowing which treatments will work best for you.

The stage of your cancer will also help the doctor decide on the best treatment for you. A stage 3 or 4 cancer is likely to respond better to treatments that treat the whole body, like chemo.

Your health and the treatment you prefer will also play a part in deciding about cancer treatment. Not all types of treatment will work for your cancer, so ask what options you have. And treatments do have side effects, so ask about what to expect with each treatment.

Don’t be afraid to ask questions. It’s your right to know what treatments are most likely to help and what their side effects may be.

Why did this happen to me?

People with cancer often ask, “What did I do wrong?” or “Why me?” Doctors don’t know for sure what causes cancer. When doctors can’t give a cause, people may come up with their own ideas about why it happened.

Some people think they’re being punished for something they did or didn’t do in the past. Most people wonder if they did something to cause the cancer.

If you’re having these feelings, you’re not alone. Thoughts and beliefs like this are common for people with cancer. You need to know that cancer is not a punishment for your past actions. Try to not blame yourself or focus on looking for ways you might have prevented cancer. Cancer is not your fault, and there’s almost never a way to find out what caused it. Instead, focus on taking good care of yourself now.

Your American Cancer Society can tell you more about cancer and cancer treatment. Call 1-800-227-2345 anytime, day or night.

How to talk to your loved ones about cancer

It can be hard to talk about cancer, even with the people you love. Learning you have cancer can stir many feelings, such as sadness, anger, and fear. Sometimes it’s hard to know how you’re feeling, much less talk to others about it.

Your loved ones may also have a hard time talking about cancer. It’s not easy for them to know what to say to help you or make you feel better.

Here are some tips to help you and your loved ones deal with cancer:

  • Tell your family and friends about your cancer as soon as you feel up to it. Sooner or later, they’ll all know you have cancer. They might feel hurt or left out if they haven’t heard about it from you.
  • When you talk to them, explain what kind of cancer you have and how it will be treated. Let them know that no one can catch it from you.
  • Allow friends and family to help you, and tell them what kind of help you need. If you need a ride to the doctor’s office or hospital, let them know. If you need help around the house, let them know that, too. There may be times when you’re not sure what you need. That’s OK. Just let them know you aren’t sure, but you’ll let them know when you are.
  • Tell the people who are closest to you how you feel. This may not be easy, but it can be a very important way to get the support you need when you need it most. If you have trouble talking about your feelings, you might find a support group or a mental health counselor to help you.
  • If you have friends or family who tell you to “cheer up” when you’re not feeling good, it’s OK to ask them to just listen, and not tell you what to do. Sometimes you need to talk about what’s going on without getting advice in return.
  • If some people are not OK with talking about your feelings, don’t be upset. Try talking to others who might listen.
  • You may not be able to do things you were doing before you got cancer. If that’s true, let your family and friends know.
  • It’s best for your family and friends to keep doing the things they did before you had cancer. They should not feel guilty about doing this.
  • If you’re feeling sad or depressed, talk to your doctor, nurse, or religious leader. You can also call the American Cancer Society at 1-800-227-2345.
  • “The first time you say, ‘I have cancer’ out loud is the hardest. The more you say it, the easier it becomes to say the words. The more I talked about my breast cancer, the easier it was for me to accept what I was going through. I found it odd that I sometimes had to cheer up those I was telling about my cancer.”

    – Helen, cancer survivor

Cancer words you may hear

These are words that you may hear your cancer care team use.

Benign (be-NINE): a tumor that’s not cancer

Biopsy (BY-op-see): taking out a piece of tissue to see if cancer cells are in it

Cancer (CAN-sur): a word used to describe more than 100 diseases in which cells grow out of control; or a tumor with cancer in it

Chemotherapy (key-mo-THER-uh-pee): the use of drugs to treat disease. The word most often refers to drugs used to treat cancer. Sometimes it’s just called “chemo.”

Malignant (muh-LIG-nunt): having cancer in it

Metastasis/Metastasized (meh-TAS-tuh-sis/meh-TAS-tuh-sized): the spread of cancer cells to distant parts of the body through the lymph system or bloodstream

Oncologist (on-KAHL-uh-jist): a doctor who treats people who have cancer

Radiation therapy (ray-dee-A-shun THER-uh-pee): the use of high-energy rays, like x-rays, to treat cancer

Remission (re-MISH-un): when signs or symptoms of cancer are all or partly gone

Stage: a word that tells whether a cancer has spread, and if so, how far

How can I learn more about my cancer?

If you have questions about cancer or need help finding resources in your area, please call the American Cancer Society. We're there when you need us – 24 hours a day, 7 days a week.

Last Medical Review: 12/08/2015
Last Revised: 12/08/2015