Melanoma

Melanoma is the most serious common skin cancer because it can spread to other parts of the body. But here is the hopeful part. Most melanomas are caught early, and an early melanoma is highly treatable.¹ This guide is an overview of the whole melanoma family. It explains the types and stages, so you can see where a diagnosis fits, then walks through how treatment changes from one stage to the next.

Key points

• Melanoma is a family of cancers, from melanoma in situ (top layer only, almost always curable) to invasive and advanced disease. Where a melanoma falls drives everything that follows.
• Most melanoma is caught early and cured with a single surgery. Advanced disease has powerful newer treatments, given by oncology.²
• Outlook depends most on how early it is found. A new or changing mole is the key warning sign.

What is melanoma?

Melanoma is a cancer of the melanocytes, the cells that give skin its color. It can appear in an existing mole or as a new spot. It shows up most on sun-exposed skin, but it can occur anywhere, including the soles, palms, and nails. The main risk factor is ultraviolet light, along with having many moles, fair skin, and a family history. What sets melanoma apart from other skin cancers is that it is more likely to spread if it is not caught early.

The melanoma family: where a diagnosis fits

Melanoma is not one thing. The biggest difference between melanomas is how deep the cancer has grown, and that is what places a diagnosis on the map below:

• Melanoma in situ (Stage 0). The earliest form. The cancer cells sit only in the top layer of skin and have not grown deeper, so it essentially cannot spread and is almost always cured by removing it. The melanoma in situ guide covers this. A common in-situ type on chronically sun-damaged skin, often on the face in older adults, is lentigo maligna (see the lentigo maligna guide).
• Invasive melanoma (Stage I–II). The melanoma has grown down into the skin but has not spread. It is staged mainly by its depth (the Breslow thickness). Surgery is the main treatment, and most are cured.
• Advanced melanoma (Stage III–IV). The melanoma has spread, either to nearby lymph nodes (Stage III) or to distant parts of the body (Stage IV). Treatment adds systemic therapy, given by oncology.

Melanoma also comes in subtypes, named for how it looks and grows: superficial spreading (the most common, spreads outward first), nodular (grows downward faster, so it can be thicker when found), lentigo maligna (on sun-damaged skin in older adults), and acral lentiginous (on the palms, soles, or under the nails). For treatment, the stage matters more than the subtype, but the subtype affects where to look and how it appears.

Warning signs: the ABCDEs

A new or changing mole is the most important clue. The ABCDE guide helps spot a worrisome mole:

• Asymmetry: one half does not match the other
• Border: edges are ragged, notched, or blurred
• Color: more than one color, or uneven color
• Diameter: larger than a pencil eraser (about 6 mm), though melanomas can be smaller
• Evolving: changing in size, shape, color, or feel, or a new spot

Another simple clue is the "ugly duckling": a mole that looks different from your others. Anything new, changing, bleeding, or itchy is worth getting checked.

How it is diagnosed and staged

A clinician examines the spot, often with a handheld magnifier (dermoscopy). Any suspicious lesion is removed and checked under the microscope (a biopsy).²

If it is melanoma, the most important number is the Breslow thickness. This is how deep the melanoma reaches into the skin, in millimeters. Thin melanomas have the best outlook. Thickness, plus whether the surface is broken (ulceration), sets the stage, which guides treatment. The current staging system (AJCC 8th edition) is built so that the small share of higher-stage tumors accounts for most of the serious outcomes.³

Treatment, by stage

Treatment follows the stage. Here is the short version of each; the deeper guides cover the details.

Melanoma in situ

Early, surface-only melanoma is removed by surgery with a narrow margin, and it is almost always cured. For lentigo maligna on the face, when surgery is difficult, nonsurgical options such as a skin cream or radiation are sometimes used. The melanoma in situ guide covers this in full.

Invasive melanoma

For invasive melanoma, surgery is the main treatment. The melanoma is removed with a margin of normal skin matched to how deep it is, and most are cured.⁴⁵ (A dedicated invasive melanoma guide, with the full treatment detail, is in progress.)

Beyond surgery, a few other treatments are used in selected cases and are led by oncology. They are not first-line, but worth knowing about:

• Radiation can be added after surgery in certain higher-risk situations, used when surgery is not a good option, or given to ease symptoms.²
• Neoadjuvant immunotherapy means immunotherapy given before surgery, for higher-risk melanoma that can still be removed. It is a newer approach, studied in recent trials and used in selected patients.⁶
• Intralesional or limb-directed therapy uses an injection into the tumor, or treatment delivered to an affected arm or leg. It can be used when melanoma comes back in the skin near the original site ("in-transit" disease).⁷

Checking the lymph nodes

For thicker melanomas, a sentinel lymph node biopsy may be offered. This checks the first lymph node the melanoma would drain to. It is mainly a staging tool: it gives the strongest single clue about outlook and helps decide whether more treatment is considered.⁸ It is not a treatment that extends survival for everyone. If that node has melanoma, doctors now often watch the area with ultrasound rather than removing all the nodes, because removing them did not improve survival in a large trial.⁹

Advanced melanoma

For advanced melanoma (spread to nodes or beyond), treatment is systemic and given by oncology:

• Immunotherapy helps the immune system attack the melanoma. After surgery for higher-risk disease it lowers the chance of return, and for spread melanoma it has meaningfully improved long-term survival.¹⁰¹¹
• Targeted pills (BRAF/MEK inhibitors) are an option for the roughly half of melanomas that carry a BRAF gene change, found by gene testing.¹²

This care is coordinated by referral to a medical oncologist.

Lowering your risk and catching it early

Most melanoma risk traces back to ultraviolet light, so sun protection lowers the chance of new melanoma over time.¹³ Because outlook depends so much on early detection, knowing your own skin and getting new or changing spots checked are the most powerful things you can do.