Learn the basics of melanoma

Receiving a cancer diagnosis often leads to many emotions, unanswered questions and concerns. Knowing what to expect, the resources available and how others have handled the disease can be a valuable asset as you navigate your cancer care options. This guide is designed to help you learn about melanoma so that you can make more informed decisions throughout your journey.

Although a diagnosis of melanoma can be frightening, new treatment options for all stages have been developing at a rapid pace over the past few years and have resulted in substantially improved outcomes. In fact, melanoma has been the focus of several new, innovative approaches in the quickly evolving field of immunotherapy.

What is melanoma?

One of many specific kinds of cancer, most melanomas arise in the skin, but they may also develop in the eye (ocular melanoma) or in the mucosal linings of the body (mucosal melanoma). This content focuses on melanoma of the skin, also known as cutaneous melanoma.

Melanoma is one of the three most common types of skin cancer. More than 3 million cases of skin cancer are diagnosed in the United States each year, but most are basal cell carcinomas and squamous cell carcinomas, which grow slowly and rarely spread or threaten life. Melanoma accounts for only a small percentage of skin cancers, however, it is much more likely to spread to nearby lymph nodes or other parts of the body, making it potentially more serious. Thankfully, most melanomas are found at an early stage, when the chance of cure is greatest.

Unfortunately, melanoma is on the rise. The number of cases has steadily increased over the past 30 years, especially among males older than 50 years and females 15 to 29 years old. In fact, melanoma has become the most common cancer among young adults 25 to 29 years old. Greater exposure to ultraviolet (UV) radiation from the sun and indoor tanning devices is thought to be the main cause of this increase, and the International Agency for Research on Cancer includes UV tanning devices on its list of the most dangerous cancer-causing substances—a list that also includes cigarettes and asbestos.

Development of melanoma

Melanoma begins in the outer layer of the skin in cells called melanocytes. These cells produce the pigment melanin, which gives color to the skin, hair and eyes. Melanocytes may also form moles that can turn into melanoma. The four main types of melanoma of the skin are superficial spreading melanoma, nodular melanoma, lentigo maligna melanoma and acral lentiginous melanoma (see Table 1).

Table 1. Types of cutaneous melanoma

Type Percentage of all melanomas Most common site on the body Comments
Superficial spreading melanoma 70% Trunk and back in men; legs and back in women Occurs most frequently in Caucasians
Nodular melanoma 15% Back in men; back and lower legs in women More aggressive type of melanoma
Lentigo maligna melanoma 10% Sun-damaged, sun-exposed sites (face, neck, arms, back of hands) Sometimes mistaken for a “sun spot,” usually in older individuals
Acral lentiginous melanoma  5% Palms, soles of the feet, underneath the nail beds Accounts for about half of all melanomas in people with dark skin, as well as African American, Asian and Hispanic individuals


In the first growth stage of melanoma, known as the radial growth phase, the melanoma grows horizontally, staying within the upper layer of the skin (epidermis) (see Figure 1). During this phase, melanomas are not likely to metastasize (spread to other areas). In the next phase, the vertical growth phase, the melanoma begins to grow down into deeper layers, such as the dermis and subcutaneous tissue, as well as up into the epidermis, and the risk for metastasis increases. Because of this, the thickness of the melanoma is the most important factor in determining its prognosis. Melanomas are classified as thin (less than 1 millimeter, about the thickness of a credit card), intermediate (1 to 4 mm) and thick (more than 4 mm). About seven of every 10 melanomas are classified as thin at the time of diagnosis, and the prognosis is best for patients with these melanomas.

Figure 1

As they spread, melanoma cells may enter the lymphatic system, a network of vessels that carry lymph (a colorless fluid) throughout the body. Once in this system, melanoma cells can spread to nearby lymph nodes and may also enter the bloodstream and travel to other parts of the body. Early treatment can stop the melanoma before it spreads through the lymphatic system to lymph nodes in the region or to distant organs, which is why early detection and treatment are so important.

In recent times, treatment outcomes have improved overall, with clinical trial research leading to improvements in various types of treatment for all stages of melanoma. For example, less extensive surgery has been proven safe for many patients, providing a better cosmetic result without compromising the outcome. Treatment has also become personalized through the use of lymphatic mapping and sentinel lymph node biopsy, which allow surgery to be tailored for each specific case of melanoma to better identify people who may benefit from having lymph nodes removed. You can learn more about lymphatic mapping and sentinel lymph node biopsy here.

Those with Stage III and IV melanoma now have more treatment options, as many new treatments—and one combination of molecular tumor cell inhibitors—have been approved by the U.S. Food and Drug Administration (FDA) since 2011. Three of these new treatments are based on research showing that a genetic mutation (abnormality) is present in some melanomas, and this abnormality can be the target of a new type of drug. This discovery is leading the way for personalized treatment of advanced melanoma, with treatment selected according to the specific characteristics of the melanoma.

Although many patients worry about the side effects of melanoma treatment, the good news is that many of these effects are minimal with treatments for thin or early-stage disease. Side effects from treatments for later-stage disease are usually not severe, and can now be managed in many ways. Talk to your doctor about the potential side effects of your treatment options and ask if there are ways to prevent or reduce them. During treatment, tell your doctor or other member of your health care team about any symptoms or side effects so they can be managed before they become severe.

Be sure to ask your doctor about all of your treatment options and talk about your preferences. Also talk about how to properly follow the guidelines to detect a second melanoma (or other skin cancer) and ways to maintain a healthy lifestyle during and after treatment. A diagnosis of melanoma can be overwhelming. By learning about your specific cancer you can make more informed decisions through the course of your cancer journey.

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