American Cancer Society - QuickFacts Thyroid Cancer

Published by the American Cancer Society/Health Promotions 250 Williams Street NW, Atlanta, Georgia 30303 USA

Copyright 2009 American Cancer Society

All rights reserved. Without limiting the rights under copyright reserved above, no part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of the publisher.

Printed in the United States of America

Cover designed by Jill Dible, Atlanta, GA
Edited by Vivian Farah McGee, Raleigh, NC
Composition by Graphic Composition, Inc.

5 4 3 2 1 09 10 11 12 13

Library of Congress Cataloging-in-Publication Data

Quickfacts thyroid cancer: what you need to know now.

p. cm. (Quickfacts)

Includes bibliographical references and index.

ISBN-13: 978-0-944235-82-9 (pbk : alk. paper)

ISBN-10: 0-944235-82-4 (pbk : alk. paper)

1. Thyroid glandCancerPopular works. I. American

Cancer Society.

RC280.T6Q53 2009

16.99444dc22

2008042607

A Note to the Reader

This information represents the views of the doctors and nurses serving on the American Cancer Societys Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.

The treatment information in this book is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.

Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Dont hesitate to ask him or her questions about your treatment options.

For more information, contact your American Cancer Society at 800-ACS-2345 or http://www.cancer.org.

Bulk purchases of this book are available at a discount. For information, contact the American Cancer Society at .

For special sales, contact us at .

TABLE OF CONTENTS

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What Is Cancer?

Cancer develops when cells in a part of the body begin to grow out of control. Although there are many kinds of cancer, they all start because of out-of-control growth of abnormal cells.

Normal body cells grow, divide, and die in an orderly fashion. During the early years of a persons life, normal cells divide rapidly. Then, after a person becomes an adult, cells in most parts of the body divide only to replace worn-out or dying cells and to repair injuries.

Because cancer cells continue to grow and divide, they are different from normal cells. Instead of dying like normal cells do, they continue to form new abnormal cells.

Cancer cells develop because of damage to DNA. DNA is in every cell and directs all of a cells activities. Most of the time when DNA becomes damaged, the body is able to repair it. In cancer cells, the damaged DNA is not repaired. People can inherit damaged DNA, which accounts for inherited cancers. Many times though, a persons DNA becomes damaged by exposure to something in the environment, like smoke.

Cancer usually forms as a tumor. Some cancers, like leukemia, do not form tumors. Instead, these cancer cells involve the blood and blood-forming organs, such as bone marrow, and circulate through other tissues where they grow. Often, cancer cells travel to other parts of the body where they begin to grow and replace normal tissue. This process is called metastasis. Regardless of where a cancer may spread, it is always named for the place it began. For instance, breast cancer that spreads to the liver is still called breast cancer, not liver cancer. Not all tumors are cancerous. Benign (noncancerous) tumors do not spread (metastasize) to other parts of the body and, with very rare exceptions, are not life threatening.

Different types of cancer can behave very differently. For example, lung cancer and breast cancer are very different diseases. They grow at different rates and respond to different treatments. Therefore, people with cancer need treatment that is aimed at their particular kind of cancer.

Cancer is the second leading cause of death in the United States. Cancer will develop in nearly half of all men and in a little over one third of all women in the United States during their lifetimes. Today, millions of people are living with cancer or have had cancer. The risk for developing most types of cancer can be reduced by changes in a persons lifestyle, for example, by quitting smoking and eating a healthier diet. The sooner a cancer is found and treatment begun, the better are a persons chances for living many years.

What Is Thyroid Cancer?

Thyroid cancer is a cancer that starts in the thyroid gland. In order to understand thyroid cancer, it helps to know about the normal structure and function of the thyroid gland. The thyroid gland is located under the Adams apple in the front part of the neck. In most people, it cannot be seen or felt. It is butterfly-shaped, with 2 lobesthe right lobe and the left lobejoined by a narrow isthmus (see picture below).

The thyroid gland contains 2 main types of cells: thyroid follicular cells and C cells (also called parafollicular cells).

The follicular cells use iodine from the blood to make thyroid hormone, which helps regulate a persons metabolism. Too much thyroid hormone (called hyperthyroidism) can cause a rapid or irregular heartbeat, sleep problems, nervousness, hunger, weight loss, and a feeling of being too warm. Too little hormone (called hypothyroidism) can cause a person to slow down, feel tired, and gain weight. The amount of thyroid hormone released by the thyroid is regulated by the pituitary gland, which is at the base of the brain and makes a substance called thyroid-stimulating hormone (TSH).

C cells (parafollicular cells) make calcitonin, a hormone that helps regulate how the body uses calcium.

Other less common cells in the thyroid gland include immune system cells (lymphocytes) and supportive (stromal) cells.

Different cancers develop from each kind of cell. These differences are important because they affect the patients outlook for survival and what type of treatment is needed.

Most tumors that develop in the thyroid gland are benign (noncancerous). Others are malignant (cancerous), which means they can spread into nearby tissues and to other parts of the body.

Benign Thyroid Enlargement and Nodules

Because the thyroid gland is right under the skin, changes in its size and shape can often be felt or even seen by patients or by their doctor.