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When Your Brother or Sister Has Cancer: A Guide for Teens

  • Posted: 12/26/2013

Learning About Cancer

What Is Cancer?
Why Do Children Get Cancer?
Will I Get Cancer, Too?
Can Doctors Cure Cancer?

Learning about cancer and your brother's or sister's treatment can help you feel less afraid. Some of what you have seen or heard about cancer may not apply. Most people feel better when they know what to expect.

Here are a few facts to remember:

  • Nothing you did, thought, or said caused your brother or sister to get cancer.
  • You can't catch cancer from another person.
  • Scientists are finding many new and better ways to find and treat cancer.
  • Most kids survive cancer.
"I got really mad at Chrissy one day. She wouldn't let me ride her bike. I got mad and said, 'I wish you were dead.' Now she has leukemia. I thought maybe it was my fault. I was scared to tell anyone because then they'd all know what I did and be mad. But my dad heard me crying one night, and got me to talk to him. He said it wasn't my fault or anybody's that Chrissy has cancer."
- Katie, age 13

 What Is Cancer?

Doctors have found more than 100 different types of cancer. Cancer is a group of many related diseases that begin in cells, the body's basic unit of life. To understand cancer, it's helpful to know what happens when normal cells become cancer cells.

Normally, cells grow and divide to make more cells only when the body needs them. This orderly process helps to keep the body healthy. Sometimes, however, cells keep dividing when new cells aren't needed. These extra cells form a mass of tissue, called a growth or tumor. Tumors can be benign or malignant:

  • Benign tumors aren't cancerous. They can often be removed and don't spread to other parts of the body.
  • Malignant tumors are cancerous. Cells in these tumors are abnormal and divide and grow without control or order. They can invade and damage nearby tissues and spread to organs in other parts of the body. The spread of cancer from one part of the body to another is called metastasis.
Illustration of normal cells on the left in comparison to abnormal cells on the right

Most cancers are named for the organ or type of cell in which they begin. For example, cancer that begins in the bone is called bone cancer. Some cancers do not form a tumor. For example, leukemia, which is the most common cancer among children, is a cancer of the bone marrow and blood.

 Why Do Children Get Cancer?

The causes of most cancers aren't known. Cancer among children does not happen that often. Scientists are still trying to learn more about why some kids get cancer and others don't.

 Will I Get Cancer, Too?

If you are worried that you may get cancer, you should know that most cancers don't run in families. You and your parents can talk to a doctor for more information.

 Can Doctors Cure Cancer?

Every year scientists discover better ways to treat cancer. That means many people are successfully treated for cancer. However, doctors are careful not to use the word "cure" until a patient remains free of cancer for several years. Cancer treatment may cause a remission, which means that the doctor can't find signs of cancer. But sometimes the cancer comes back. This is called a relapse or recurrence. Whether your brother or sister will be cured of cancer depends on many things. No booklet can tell you exactly what to expect. It is better to talk with your parents and your sibling's doctor or nurse.

Where to go for more information

To learn more about the type of cancer your brother or sister has, visit the National Cancer Institute's (NCI) Web site ( You can also call NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237) to talk with an information specialist. All calls are free and confidential.