Melanoma is a cancer that begins in melanocytes, the cells that give skin its color, and it is the most serious form of skin cancer because it can spread to other parts of the body if it is not found early. It makes up only a small share of skin cancer cases, yet it causes the large majority of skin cancer deaths. The reassuring part is that melanoma is highly treatable when caught early, and most cases are curable with prompt care, especially when people know the warning signs and get regular skin checks. This guide explains what melanoma is, its symptoms, causes, how it is diagnosed, the treatments available, and the latest research.
What is melanoma?
Melanocytes are the cells that produce melanin, the pigment that gives skin, hair, and eyes their color and helps protect skin from sun damage. Melanoma develops when melanocytes begin to grow and divide abnormally, forming a tumor that can invade nearby tissue and, if untreated, spread to lymph nodes and distant organs. Most melanomas start in the skin, often within an existing mole or as a new pigmented spot, but the disease can also arise in less obvious places, including under the nails, in the eyes, and in mucous membranes that never see the sun.
Melanoma is far less common than other types of skin cancer, but it causes the large majority of skin cancer deaths because of how readily it can spread. The outlook depends heavily on timing: five-year relative survival is above 99% when melanoma is caught while still localized to the skin, about 76% once it reaches nearby lymph nodes, and around 35% after it spreads to distant organs. The overall five-year survival rate across all stages combined is about 95%, showing how much early detection changes the picture. Risk also shifts with age and sex: before 50, melanoma is more common in women, and after 50, more common in men.
Symptoms of melanoma
The clearest way to recognize a potential melanoma is the ABCDE rule, a checklist that helps separate a suspicious mole from a harmless one. Asymmetry means one half of a mole does not match the other half in shape. Border refers to edges that are ragged, notched, or blurred rather than smooth. Color variation means shades of brown, black, tan, red, white, or blue appear within the same spot. Diameter flags moles larger than about 6 millimeters, roughly the size of a pencil eraser, although melanoma can be smaller when caught early. Evolving describes any mole that is changing in size, shape, color, or texture over weeks to months. Any single one of these features is worth having a clinician take a look.
Beyond the ABCDE signs, other clues can point to melanoma. A new spot, or one that looks noticeably different from a person’s other moles, sometimes called the ugly duckling sign, deserves attention, as does any mole that begins to itch, bleed, or fails to heal. While melanoma most often develops on skin that gets sun exposure, such as the back, legs, arms, and face, it can also appear in places that are rarely examined, including the scalp, the soles of the feet, under the nails, and, less commonly, the eyes. A systematic skin self-exam paired with a periodic professional skin check helps catch these changes early.
What causes melanoma and its risk factors
The single most important, and most preventable, cause of melanoma is ultraviolet radiation from sunlight, tanning beds, or sun lamps, which damages the DNA inside melanocytes and can trigger the uncontrolled growth that becomes melanoma. Certain traits raise risk further: fair skin, light-colored hair or eyes, and a tendency to freckle or sunburn easily all mean skin has less natural protection against UV damage. Having many moles, more than 50, or moles that look atypical also raises risk, and about 1 in 10 people with melanoma has a family member who had the disease, pointing to an inherited component in some cases.
A weakened immune system is another important risk factor: people who have received an organ transplant or who live with HIV develop melanoma more often, since a less active immune system is less able to catch abnormal cells before they grow into cancer. This same vulnerability raises the risk of other cancers, too. Exploring the symptoms and causes of lymphoma shows how immune suppression can affect more than one type of cancer. About half of all melanomas also carry a change in the BRAF gene, which has directly shaped treatment by making the tumor a target for specific drugs. Because ultraviolet exposure drives most cases, protecting skin by seeking shade, wearing broad-spectrum sunscreen of SPF 30 or higher, covering up with protective clothing and a hat, and avoiding tanning beds altogether remains the most effective way to lower risk.
How melanoma is diagnosed
Diagnosis starts with a visual skin examination, often helped by dermoscopy, a technique using a special magnifying light to study a mole’s pattern and color. Any suspicious spot is then sampled with a skin biopsy, which may be a shave, punch, incisional, or excisional biopsy depending on the lesion’s size and location, and examined under a microscope to confirm whether melanoma is present. That same sample lets a pathologist measure the Breslow depth, how many millimeters deep the tumor has grown, one of the strongest predictors of outcome and a key part of the tumor, or T, category used in staging.
| Breslow depth | What it means for staging |
|---|---|
| Less than 0.8 mm | Thinnest tumors, generally staged T1, often the most curable |
| 0.8 mm to 4.0 mm | Intermediate thickness, generally staged T2 to T3 |
| More than 4.0 mm | Thickest tumors, staged T4, with a higher risk of spread |
For tumors of intermediate thickness, a sentinel lymph node biopsy checks whether melanoma cells have reached the nearest lymph nodes, helping determine the nodal, or N, category and how aggressively the disease should be treated. In higher-stage disease, imaging such as CT, PET, or MRI scans may look for spread to distant organs. Blood testing also plays a role in advanced, stage IV disease: measuring the LDH blood test is built directly into the staging system, since a normal versus an elevated level separates patients into different prognostic subgroups and generally signals how heavy the burden of disease is.
Treatment options for melanoma
Treatment for melanoma is guided mainly by how thick and how advanced the tumor is. Early, thin melanomas are often cured with surgery alone, removing the tumor along with a margin of healthy surrounding skin. As melanoma thickens or spreads to lymph nodes or distant organs, treatment increasingly relies on systemic therapies that work throughout the body rather than on the skin alone.
| Approach | Role |
|---|---|
| Surgical excision | Removes the tumor and a margin of healthy skin; the main treatment for early, localized melanoma |
| Immunotherapy | Helps the immune system recognize and attack melanoma cells; used in higher-stage and advanced disease, and increasingly before surgery |
| Targeted therapy | Drugs aimed at specific mutations, such as BRAF, that drive tumor growth in about half of melanomas |
| Radiation therapy | Used in select cases, such as after lymph node surgery or to ease symptoms from disease that has spread |
For melanoma that has spread to nearby lymph nodes or beyond, treatment now often combines approaches. Immunotherapy drugs called checkpoint inhibitors, which release the brakes that let cancer hide from the immune system, are used both after surgery and increasingly before it, sometimes combining two checkpoint inhibitors for a stronger effect. When a tumor carries a BRAF mutation, targeted therapy can be added or used alone, particularly when a fast response is needed. Because these are powerful medications with distinct side effects, treatment decisions are made individually, weighing tumor thickness, staging, BRAF status, and each person’s overall health.
Living with melanoma and long-term outlook
Most people diagnosed with melanoma, especially at an early stage, go on to live long, healthy lives, and many need no further cancer treatment once the initial tumor is removed. Long-term follow-up typically includes regular skin exams, since people who have had one melanoma are at higher risk of developing another, along with periodic checks of the lymph nodes near the original site. For those diagnosed at a more advanced stage, follow-up may also include imaging scans and blood tests to watch for any sign that the disease has returned.
Sun protection remains important for life, since ongoing UV exposure raises the risk of new melanomas as well as other skin cancers. Learning to perform a thorough monthly skin self-exam, and asking a family member to help check hard-to-see areas like the back and scalp, gives people confidence to catch any change early. Because melanoma can sometimes run in families, first-degree relatives of someone diagnosed with melanoma may also benefit from their own regular skin checks. With early detection, appropriate treatment, and consistent follow-up, the long-term outlook for melanoma continues to improve.
Latest scientific advances in melanoma research
According to PubMed-indexed research, giving immunotherapy before surgery is emerging as a more effective strategy than giving it only afterward for higher-risk, operable melanoma. In the phase 3 NADINA trial, patients with resectable stage III melanoma who received ipilimumab and nivolumab before surgery had a 12-month event-free survival of 83.7%, compared with 57.2% for those who received adjuvant nivolumab alone after surgery (Blank et al., 2024). What this means for you: receiving immunotherapy before the operation, not only after it, may substantially lower the chance of recurrence for resectable stage III melanoma.
Research is also advancing on cancer vaccines personalized to a patient’s own tumor. In the KEYNOTE-942 trial, adding an individualized messenger RNA vaccine made from each patient’s tumor mutations to the immunotherapy drug pembrolizumab after surgery raised 18-month recurrence-free survival to 79%, compared with 62% for pembrolizumab alone, in people with resected high-risk melanoma (Weber et al., 2024). What this means for you: a vaccine tailored to a person’s own cancer, layered onto standard immunotherapy, may further reduce the chance that melanoma returns after surgery. A five-year update of this trial found the benefit is lasting rather than temporary, with continued reductions in recurrence and distant metastasis, a favorable trend in overall survival, and no new safety concerns after a median follow-up of just over five years (Khattak et al., 2026). What this means for you: this personalized vaccine approach looks like a durable benefit rather than a short-lived signal, supporting its continued testing in larger trials and offering encouragement for people with high-risk melanoma.
Glossary of key melanoma terms
| Term | Definition |
|---|---|
| Melanocyte | The pigment-producing skin cell from which melanoma develops. |
| ABCDE rule | A checklist, asymmetry, border, color, diameter, evolving, used to spot a mole that could be melanoma. |
| Breslow depth | The thickness of a melanoma in millimeters, measured on a biopsy, used to help stage the tumor. |
| Sentinel lymph node biopsy | A procedure that removes the first lymph node or nodes melanoma would likely reach, to check for spread. |
| BRAF mutation | A genetic change found in about half of melanomas that can be targeted with specific drugs. |
| Lactate dehydrogenase (LDH) | A blood marker checked in advanced melanoma; an elevated level can point to a heavier burden of disease. |
| Immunotherapy | Treatment that helps a person’s own immune system recognize and attack cancer cells. |
Frequently asked questions about melanoma
What does melanoma look like?
Melanoma often looks like a mole or dark spot that stands out from a person’s other moles, following the ABCDE pattern: asymmetrical, with an irregular border, more than one color, a diameter over about 6 millimeters, or a shape that keeps changing. Colors range from brown and black to tan, red, white, or blue, so any new or changing spot is worth having checked.
What are the first signs of melanoma?
The earliest sign is usually a change in an existing mole, or a new one that looks different from a person’s other moles, sometimes called the ugly duckling sign. A mole that itches, bleeds, or will not heal is another early clue. Learning the ABCDE warning signs helps people catch a problem while it is easiest to treat.
What causes melanoma?
Melanoma is caused by DNA damage in melanocytes, the pigment-producing skin cells, most often from ultraviolet radiation in sunlight, tanning beds, or sun lamps. Risk is higher with fair skin, light hair or eyes, many moles, a family history of melanoma, or a weakened immune system.
What are the stages of melanoma?
Melanoma is staged from 0 to IV based on the Breslow depth, or how deep the tumor has grown, whether it has ulcerated, whether it has reached nearby lymph nodes, and whether it has spread to distant organs. Earlier stages stay confined to the skin, while stage IV means it has reached distant sites such as the lungs, liver, or brain.
What is the survival rate for melanoma?
Survival depends heavily on the stage at diagnosis. Five-year relative survival is above 99% when melanoma is still localized to the skin, about 76% once it reaches nearby lymph nodes, and around 35% after it spreads to distant organs. The overall five-year survival rate across all stages combined is about 95%.
How is melanoma treated?
Early melanoma is usually treated with surgery to remove the tumor and a margin of surrounding skin, which is often curative on its own. More advanced melanoma relies on systemic therapies, including immunotherapy and targeted therapy for tumors with specific mutations such as BRAF, sometimes combined with surgery or radiation.
Sources
- American Academy of Dermatology — The ABCDEs of Melanoma — AAD, 2024 — aad.org
- American Cancer Society — Melanoma Skin Cancer Survival Rates by Stage — American Cancer Society, 2025 — cancer.org
- Mayo Clinic — Melanoma: Symptoms and Causes — Mayo Clinic, 2024 — mayoclinic.org
- Blank CU, et al. — Neoadjuvant Nivolumab and Ipilimumab in Resectable Stage III Melanoma — New England Journal of Medicine, 2024 — doi.org/10.1056/NEJMoa2402604
- Weber JS, et al. — Individualised neoantigen therapy mRNA-4157 (V940) plus pembrolizumab versus pembrolizumab monotherapy in resected melanoma (KEYNOTE-942): a randomised, phase 2b study — The Lancet, 2024 — doi.org/10.1016/S0140-6736(23)02268-7
- Khattak A, et al. — Intismeran Autogene Plus Pembrolizumab Versus Pembrolizumab Alone in High-Risk Resected Melanoma: 5-Year Update of the Randomized Phase IIb KEYNOTE-942 Study — Journal of Clinical Oncology, 2026 — doi.org/10.1200/JCO-26-00835
Further reading
- See how melanoma fits into the wider picture in this guide to the symptoms, causes, and treatment of skin cancer.
- Build confidence reading your results in this guide to reference ranges, flags, and next steps on a lab report.
Understand your lab results with BloodSense
Melanoma is diagnosed mainly through skin exams and biopsy rather than a blood test, but once the disease reaches an advanced stage, a marker like LDH becomes part of how doctors track it and plan care. Seeing where a value like LDH sits against its reference range, and understanding what a change over time might mean, can make follow-up appointments and treatment discussions easier to follow. BloodSense translates a full lab report into plain language, showing what each marker means and helping you track changes over time instead of reading one line in isolation.
