The American Cancer Society is a grassroots organization committed to fighting cancer through balanced programs of research, education, patient service, rehabilitation, and advocacy. Its goals emphasize prevention, early detection, and screening; comprehensive treatment information; answers to questions about insurance, money, and planning for the future; and strategies for coping with the physical symptoms and emotional effects of cancer. They are based in Atlanta.

Melanoma Skin Cancer

What You Need to Know — Now

By American Cancer Society

American Cancer Society / Health Promotions

Copyright © 2012 American Cancer Society
All rights reserved.
ISBN: 978-1-60443-038-7

Contents

Your Melanoma Skin Cancer,
Risk Factors and Causes,
Prevention and Detection,
Diagnosis and Staging,
Treatment,
Questions to Ask,
After Treatment,
Latest Research,
Resources,
Glossary,
Index,

CHAPTER 1

Your Melanoma Skin Cancer

What Is Cancer?

The body is made up of hundreds of millions of living cells. Normal body cells grow, divide, and die in an orderly fashion. During the early years of a person's life, normal cells divide faster to allow the person to grow. After the person becomes an adult, most cells divide only to replace worn-out or dying cells or to repair injuries.

Cancer begins when cells in a part of the body start to grow out of control. There are many kinds of cancer, but they all start because of out-of-control growth of abnormal cells. Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells. Cancer cells can also invade (grow into) other tissues, something that normal cells cannot do. Growing out of control and invading other tissues are what makes a cell a cancer cell.

Cells become cancer cells because of damage to DNA. DNA is in every cell and directs all its actions. In a normal cell, when DNA is damaged, the cell either repairs the damage or the cell dies. In cancer cells, the damaged DNA is not repaired, but the cell does not die like it should. Instead, this cell goes on making new cells that the body does not need. These new cells will all have the same damaged DNA as the first cell.

People can inherit damaged DNA, but most DNA damage is caused by mistakes that happen while the normal cell is reproducing or by something in the environment. Sometimes the cause of the DNA damage is something obvious, like cigarette smoking. Often, however, no clear cause is found.

In most cases, the cancer cells form a tumor. Some cancers, such as leukemia, rarely form tumors. Instead, these cancer cells involve the blood and blood-forming organs and circulate through other tissues where they grow.

Cancer cells often travel to other parts of the body, where they begin to grow and form new tumors that replace normal tissue. This process is called metastasis. It happens when the cancer cells get into the bloodstream or lymph vessels of the body.

No matter where a cancer may metastasize, or spread, it is always named for the place where it started. For example, breast cancer that has spread to the liver is still called breast cancer, not liver cancer. Likewise, prostate cancer that has spread to the bone is metastatic prostate cancer, not bone cancer.

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. That is why people with cancer need treatment that is aimed at their particular kind of cancer.

Not all tumors are malignant. Tumors that are not cancer are called benign. Benign tumors can cause problems — they can grow very large and press on healthy organs and tissues. However, they cannot invade other tissues. Because they cannot invade other tissues, they also cannot metastasize, or spread, to other parts of the body. These tumors are almost never life threatening.

What Is Melanoma?

Melanoma is a cancer that starts in a certain type of skin cell. To understand melanoma, it helps to know about the normal structure and function of the skin.

Normal Skin

Skin is the largest organ in your body. It does several different things:

• covers the internal organs and protects them from injury

• serves as a barrier to germs such as bacteria

• prevents the loss of too much water and other fluids

• helps control body temperature

The skin has the following 3 layers:

• epidermis

• dermis

• subcutis

Epidermis

The top layer of skin is the epidermis. The epidermis is very thin, averaging only 0.2 millimeters (mm) thick (about 1/100 of an inch). It protects the deeper layers of skin and the organs of the body from the environment.

Keratinocytes are the main cell type of the epidermis. These cells make an important protein called keratin, which gives the skin strength and flexibility and makes the skin waterproof.

The epidermis itself is made up of 3 sublayers. The outermost part of the epidermis is called the stratum corneum, or horny layer. It is composed of dead keratinocytes that are continually shed as new cells form. The cells in this layer are called squamous cells because of their flat shape.

Just below the stratum corneum are living keratinocytes. Below that is the basal layer, the inner layer of the epidermis. The cells of the basal layer, called basal cells, continually divide to form new keratinocytes. These new keratinocytes replace the older keratinocytes that slough off the skin's surface.

Melanocytes, the cells that can become melanoma, are also present in the epidermis. These skin cells make the brown pigment called melanin, which makes skin tan or brown. Melanin protects the deeper layers of the skin from some of the harmful effects of the sun.

The epidermis is separated from the deeper layers of skin by the basement membrane. The basement membrane is an important structure. When a cancer becomes more advanced, it generally grows through the basement membrane.

Dermis

The middle layer of the skin is called the dermis. The dermis is much thicker than the epidermis. It contains hair follicles, sweat glands, blood vessels, and nerves that are held in place by a protein called collagen. Collagen is made by cells called fibroblasts and gives the skin its resilience and strength.

Subcutis

The deepest layer of the skin is called the subcutis. The subcutis and the lowest part of the dermis form a network of collagen and fat cells. The subcutis helps the body conserve heat and has a shock-absorbing effect that helps protect the body's organs from injury.

Benign Skin Tumors

Many types of benign (noncancerous) tumors can develop from different types of skin cells.

Melanocytic tumors

A mole, or nevus, is a benign skin tumor that develops from melanocytes. Nearly all moles are harmless, but having some types may raise your risk of melanoma. See the section "What Are The Risk Factors for Melanoma?" on page 11 for more information about moles.

A Spitz nevus is a kind of skin tumor that sometimes looks like melanoma. These tumors are generally benign and do not spread. However, sometimes doctors have trouble telling Spitz nevi from true melanomas, even when looking at them under a microscope. Therefore, they are often removed, just to be safe.

Other benign tumors

Benign tumors that develop from other types of skin cells include the following:

• seborrheic keratoses: tan, brown, or black raised spots with a "waxy" texture or rough...