Melanoma, also known as malignant melanoma, is a type of cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin but may rarely occur in the mouth, intestines or eye (uveal melanoma).
In women, they most commonly occur on the legs, while in men they most commonly occur on the back. About 25% of melanomas develop from moles.
What are melanocytes
Melanocytes are skin cells found in the upper layer of skin. They produce a pigment known as melanin, which gives skin its color.
The primary cause of melanoma is ultraviolet light (UV) exposure in those with low levels of the skin pigment melanin.
The UV light may be from the sun or other sources, such as tanning devices. Those with many moles, a history of affected family members and poor immune functionimmune function are at greater risk. A number of rare genetic conditions such as xeroderma pigmentosum also increase the risk.
Diagnosis is by biopsy and analysis of any skin lesion that has signs of being potentially cancerous.
Using sunscreen and avoiding UV light may prevent melanoma. Treatment is typically removal by surgery. In those with slightly larger cancers, nearby lymph nodes may be tested for spread (metastasis). Most people are cured if spread has not occurred. For those in whom melanoma has spread, immunotherapy, biologic therapy, radiation therapy or chemotherapy may improve survival.
With treatment, the five-year survival rates in the United States are 99% among those with localized disease, 65% when the disease has spread to lymph nodes and 25% among those with distant spread.
The likelihood that melanoma will reoccur or spread depends on its thickness, how fast the cells are dividing and whether or not the overlying skin has broken down.
The risk of melanoma seems to be increasing in people under 40, especially women.
The following factors may also contribute to an increased risk of skin cancer:
- A high density of freckles or a tendency to develop freckles following exposure to the sun
- A high number of moles
- Five or more atypical moles
- The presence of actinic lentigines, also known as liver spots or age spots
- Giant congenital melanocytic nevi, a type of brown birthmark
- Pale skin that does not tan easily and tends to burn
- light eyes
- Red or light hair
- High sun exposure, particularly if it produces blistering sunburn, and if sun exposure is intermittent rather than regular
- Older age
- A family or personal history of melanoma
- A previous organ transplant
Knowing the warning signs of skin cancer can help ensure that cancerous changes are detected and treated before the cancer has spread. Melanoma can be treated successfully if it is detected early.
Melanoma is the most dangerous type of skin cancer. Globally, in 2012, it newly occurred in 232,000 people.
In 2015, there were 3.1 million people with active disease, which resulted in 59,800 deaths.
Australia and New Zealand have the highest rates of melanoma in the world. There are also high rates in Northern Europe and North America, while it is less common in Asia, Africa and Latin America. In the United States melanoma occurs about 1.6 times more often in men than women.
Changes in a mole that can indicate melanoma include an increase in size, irregular edges, change in color, itchiness or skin breakdown.
Advances in treatment have led to the largest yearly declines in deaths due to melanoma ever recorded for this skin cancer, results of a new study suggest.
Led by researchers at NYU Grossman School of Medicine, its Perlmutter Cancer Center, and Harvard University, the study showed that death rates among white Americans the group that accounts for almost all cases climbed 7.5 percent between 1986 and 2013, but then dropped by nearly 18 percent over the next three years.
The death rates were for metastatic melanoma, the aggressive form that spreads from the skin to other organs, such as the lung, liver, or brain.
The authors say the size of the declines outstrip comparable decreases in cancers of the prostate, breast, and lung, three other common forms of cancer.
They also note that the unrivaled drop in melanoma deaths coincided with the introduction of 10 new therapies for the skin cancer. These treatments either harness the body’s immune system to fight the disease or directly target melanoma cells that have a specific gene mutation.
“Our findings show how quickly patients and physicians accepted these new drugs because they profoundly reduce deaths from melanoma,”
says co-senior study author David Polsky, MD, PhD.
“These therapies are now considered the backbone of how we treat this cancer,”
says Polsky, the Alfred W. Kopf, M.D. Professor of Dermatologic Oncology at NYU Langone Health and its Perlmutter Cancer Center.
The report was published in the American Journal of Public Health, is the first to highlight the role of these new drugs in helping Americans survive melanoma, says Polsky, who is also a professor in the Department of Pathology at NYU Langone.
According to some estimates, melanoma is among the most common forms of cancer in the United States, with about 100,000 new cases occurring every year. Once tumors spread throughout the body, melanoma had been notoriously difficult to treat, and conventional treatment methods like chemotherapy have limited effect against the disease.
While the specific causes of melanoma are unclear, genetics and exposure to UV radiation in sunlight and tanning beds are known to increase risk, particularly among fairer-skinned people.
The newer therapies, which came into use in the last decade, are far more effective and less toxic than standard chemotherapy, but are much more expensive, the investigators say.
The drugs fall into two broad categories: those that target the BRAF gene, which is mutated in a little less than half of melanoma patients; and immune checkpoint inhibitors, which prevent melanoma tumors from tricking the immune system into ignoring the cancer.
For the study, researchers analyzed new cases and deaths from melanoma collected by the National Cancer Institute and the Centers for Disease Control and Prevention. These numbers spanned from 1986 to 2016 and involved nearly a million Americans.
Polsky notes that the steep drop in deaths cannot be readily explained by better detection methods because death rates did not drop steadily over time, but sharply. In addition, many health care groups have been pushing for early detection exams since the 1980s, so the timing of these declines matches up better with the introduction of the new therapies.
Nevertheless, the researchers caution that early detection is still important, allowing for less toxic forms of treatment and lowered health care costs.
They emphasized that prevention, avoiding excessive UV light exposure, and promptly seeking medical care when there is a change in the skin’s appearance, are crucial to reducing the risk of developing metastatic melanoma.
Polsky says future studies should investigate socioeconomic factors that may affect access to the newer therapies, as well as the effect of these treatments on other ethnic groups.