Melanoma

What it is

Overview

Melanoma is the most dangerous form of skin cancer. Though it accounts for only about 1% of skin cancer cases, it causes the vast majority of skin cancer deaths. It arises from melanocytes, the pigment-producing cells in the skin. When detected early, it is highly treatable — but once it spreads to lymph nodes or organs, treatment becomes far more challenging.

Biology

How It Develops

UV radiation from sunlight or tanning beds damages melanocyte DNA, particularly causing mutations in the BRAF gene (present in ~50% of melanomas). These mutations activate growth signaling pathways that drive uncontrolled proliferation. Melanoma can arise from existing moles or develop in seemingly normal skin. It spreads via lymphatic and blood vessels.

Warning signs

Symptoms

• —A mole that changes in size, shape, or color
• —A lesion with an irregular border or multiple colors
• —A new growth on the skin that looks unusual
• —A sore that doesn't heal
• —Spread of pigment from the border into surrounding skin
• —Redness, swelling, or satellite nodules (advanced)

Detection

Diagnosis Methods

• —Skin examination (dermatoscopy)
• —Excisional biopsy (gold standard)
• —Sentinel lymph node biopsy
• —CT, MRI, and PET scan for staging
• —Genetic testing (BRAF, NRAS, c-KIT mutations)

Medical care

Treatment Options

• —Wide surgical excision
• —Targeted therapy (BRAF/MEK inhibitors: vemurafenib, dabrafenib)
• —Immunotherapy (checkpoint inhibitors: pembrolizumab, nivolumab, ipilimumab)
• —Combination targeted + immunotherapy
• —Radiation therapy (for brain metastases)
• —Isolated limb perfusion (for limb melanoma)

Data

Statistics

Prevention

Risk Factors

• —UV radiation from sun or tanning beds
• —Fair skin, light eyes, and red or blonde hair
• —History of sunburns, especially in childhood
• —Large number of moles or atypical moles
• —Family or personal history of melanoma
• —Weakened immune system

Further reading

Resources