When you have melanoma, pigment-producing cells in your skin have turned cancerous. What happens next depends almost entirely on how deep the melanoma has grown and whether it has spread. Caught early, the five-year survival rate is effectively 100%. If the cancer has reached distant organs, that number drops to 34%. The gap between those two numbers makes understanding the process, from diagnosis through treatment, genuinely important.
How Melanoma Starts and Grows
Melanoma begins in melanocytes, the cells that give your skin its color. UV radiation from sunlight or tanning beds can damage the DNA inside these cells, trigger abnormal cell division, suppress the skin’s local immune defenses, and generate harmful molecules called free radicals. Over time, one or more of these mechanisms can cause a melanocyte to start growing out of control.
In its earliest phase, called the radial growth phase, the cancer spreads outward within the top layer of skin (the epidermis). At this point it hasn’t developed the ability to reach other parts of your body. If it progresses to the vertical growth phase, the cells push downward into the deeper layer of skin (the dermis) and gain the potential to enter blood vessels or lymph channels. That’s when melanoma becomes dangerous, because once cells reach those pathways, they can travel to distant organs.
What the Diagnostic Process Looks Like
Most melanomas are first noticed as a new or changing mole. You, a partner, or a dermatologist spots something suspicious, and the next step is a biopsy: a doctor removes part or all of the spot so a pathologist can examine it under a microscope. The pathologist measures how deep the melanoma extends into the skin, reported in millimeters as the Breslow thickness. This single number drives nearly every decision that follows.
If the melanoma is thicker than 1.0 mm, your surgical team will typically recommend a sentinel lymph node biopsy. This procedure identifies the first lymph node(s) where cancer would drain if it had started to spread. A tracer is injected near the melanoma site, and the surgeon removes the node that picks up the tracer to check it for cancer cells. For very thin melanomas (under 0.8 mm with no ulceration), this step usually isn’t needed because the risk of spread is very low. For melanomas between 0.8 and 1.0 mm, or those under 0.8 mm that show ulceration, it’s a judgment call you and your doctor make together.
Understanding Your Stage
Staging tells you how far the melanoma has progressed and shapes your treatment plan. The system uses three factors: the primary tumor’s thickness and characteristics (T), whether nearby lymph nodes are involved (N), and whether the cancer has spread to distant sites (M).
- Stage I: The melanoma is thin (generally under 2 mm) and confined to the skin, with no lymph node involvement. This is the most common stage at diagnosis.
- Stage II: The tumor is thicker (over 1 mm, sometimes over 4 mm) but still hasn’t reached the lymph nodes. Thicker tumors and those with surface ulceration carry higher risk.
- Stage III: Cancer cells have been found in nearby lymph nodes or in the skin between the original melanoma and the nearest lymph node group. Stage III is further divided into four subgroups (IIIA through IIID) based on how many nodes are involved and the characteristics of the original tumor.
- Stage IV: The melanoma has spread to distant organs. The specific designation depends on where it has traveled and whether a blood marker called LDH is elevated. Brain metastases get their own category because they require distinct management.
Surgery: The Primary Treatment
For melanoma that hasn’t spread beyond the skin, surgery is the main treatment. After the initial biopsy, you’ll have a second procedure called a wide local excision, where the surgeon removes additional tissue around the biopsy site to make sure no cancer cells remain at the edges. The amount of surrounding skin removed depends on how thick the melanoma was:
- Melanoma in situ (confined to the epidermis): 0.5 to 1 cm margin
- Up to 1 mm thick: 1 cm margin
- 1 to 2 mm thick: 1 to 2 cm margin
- Over 2 mm thick: 2 cm margin
These margins may sound small, but they translate to a noticeable incision, especially on areas like the face or hands. Most wide excisions are done under local anesthesia as outpatient procedures. The wound is typically closed with stitches, and recovery takes a few weeks. For larger excisions, a skin graft or flap may be needed.
Treatment for Advanced Melanoma
When melanoma has spread to lymph nodes or distant organs, surgery alone isn’t enough. The two main categories of systemic treatment have transformed outcomes over the past decade.
Immunotherapy
The most widely used approach helps your immune system recognize and attack melanoma cells. Your immune system has built-in “brakes” that prevent it from attacking your own tissues, and melanoma can exploit those brakes to hide. Drugs like pembrolizumab and nivolumab release those brakes, letting immune cells find and destroy cancer cells throughout the body. These treatments are given as IV infusions, typically every few weeks. Side effects stem from the immune system becoming overactive: skin rashes, fatigue, and sometimes inflammation in organs like the thyroid, liver, or intestines.
Targeted Therapy
About half of all melanomas carry a specific mutation in a gene called BRAF. If your tumor tests positive for this mutation, you may be treated with a combination of two oral medications: one that blocks the BRAF protein and another that blocks a related protein called MEK. These drugs work together to shut down the signaling pathway that drives the cancer’s growth. Targeted therapy tends to shrink tumors quickly, though the cancer can eventually develop resistance, which is why immunotherapy is often considered as well.
Where Melanoma Spreads and What That Feels Like
Metastatic melanoma most commonly reaches the lymph nodes, lungs, brain, liver, and bones. The symptoms you experience depend on where the cancer lands. Lung involvement can cause a persistent cough or shortness of breath. Brain metastases may produce headaches or seizures. Swollen lymph nodes are sometimes the first sign of spread, noticeable as firm lumps under the skin in the armpit, groin, or neck. Liver involvement often shows up as unexplained weight loss or loss of appetite. Bone metastases cause deep pain or, in some cases, fractures from minor injuries.
Not all metastases cause symptoms right away. Some are found on routine imaging scans during follow-up, which is why surveillance after treatment is a key part of living with a melanoma history.
Survival Rates by Stage
The numbers paint a clear picture of why early detection matters so much. Based on data from the SEER cancer registry covering 2016 through 2022:
- Localized melanoma (still confined to the skin): 100% five-year relative survival
- Regional spread (cancer in nearby lymph nodes): 76% five-year relative survival
- Distant spread (metastasis to other organs): 34% five-year relative survival
These are population averages, and individual outcomes vary based on the specific location and volume of spread, your overall health, and how the cancer responds to treatment. The distant-stage number, while sobering, has improved significantly over the past decade thanks to immunotherapy and targeted drugs. Before these treatments became available, the five-year survival for metastatic melanoma was in the single digits.
Life After Treatment
Once your initial treatment is complete, you enter a surveillance phase. This typically involves regular skin checks with a dermatologist and periodic physical exams to feel for enlarged lymph nodes. For higher-stage melanomas, imaging scans (usually CT or PET scans) are part of the routine for several years. The schedule is more frequent in the first two to three years, when recurrence risk is highest, then gradually spaces out.
Having had one melanoma raises your risk of developing another. You’ll need to monitor your skin for life, wear sun protection daily, and avoid tanning beds entirely. Monthly self-exams, where you check your entire body for new or changing moles, become a permanent habit. Many people find that the anxiety around follow-up appointments fades with time, especially as each clear visit builds confidence that the cancer hasn’t returned.