If you have melanoma, what happens next depends almost entirely on how deep the tumor has grown into your skin. Caught early and still confined to its original site, melanoma has a 100% five-year survival rate. Found after it has spread to distant organs, that number drops to 34%. The gap between those two numbers is why the first thing your doctor will do is figure out exactly how far the cancer has progressed, then build a treatment plan around that answer.
How Melanoma Is Diagnosed and Staged
Melanoma is confirmed through a biopsy, where a doctor removes the suspicious mole or spot (or a piece of it) and sends it to a pathologist. The pathologist examines the tissue under a microscope and measures something called Breslow depth: how far down, in millimeters, the melanoma cells have penetrated below the skin’s surface. This single measurement is the most important factor in determining your stage and your outlook.
The staging system works like this:
- Stage I: The tumor is 2 mm thick or less. Stage IA means it’s 1 mm or thinner without ulceration (a break in the skin over the tumor). Stage IB means it’s up to 2 mm without ulceration.
- Stage II: The tumor is thicker or has ulceration. Stage IIA covers tumors 1.1 to 2 mm with ulceration, or 2.1 to 4 mm without it. Stage IIB and IIC describe tumors thicker than 4 mm, with IIC reserved for those that are both thick and ulcerated.
- Stage III: Melanoma has spread to nearby lymph nodes or developed satellite tumors near the original site.
- Stage IV: The cancer has reached distant organs like the lungs, liver, brain, or bones.
Ulceration matters at every stage because it signals a more aggressive tumor. Two melanomas of identical thickness can be staged differently based on whether the skin above them has broken down.
Checking Whether It Has Spread
For very thin melanomas (under 0.8 mm with no ulceration), the chance of spread is low enough that no further surgical investigation is typically needed. For tumors between 0.8 and 1 mm, or thinner tumors that are ulcerated, your doctor may discuss a sentinel lymph node biopsy. This procedure identifies the first lymph node that drains from the tumor site, removes it, and checks it for cancer cells.
For melanomas thicker than 1 mm, a sentinel lymph node biopsy is a standard recommendation. The result tells your team whether cancer cells have begun migrating beyond the skin, which changes both your stage and your treatment options. For very thick tumors (over 4 mm), the biopsy is still often recommended, though the conversation with your doctor will weigh the benefits against the small surgical risks involved.
If there’s concern about distant spread, imaging scans of the chest, abdomen, pelvis, or brain help identify whether melanoma has reached other organs.
Surgery: The First Line of Treatment
Nearly every melanoma patient undergoes a procedure called wide local excision. The surgeon removes the original tumor site along with a margin of healthy-looking skin around it to catch any stray cancer cells. The size of that margin depends on tumor thickness:
- 1 mm thick or less: 1 cm margin of surrounding skin
- 1 to 2 mm thick: 1 to 2 cm margin
- Thicker than 2 mm: 2 cm margin
For thin, early-stage melanomas, this surgery is often the only treatment needed. The wound is typically closed with stitches the same day, and most people recover at home over a few weeks. For melanomas on the face or hands where skin is tight, the surgeon may need to use a skin graft or flap to close the site.
What Treatment Looks Like for Advanced Melanoma
When melanoma has reached the lymph nodes or spread beyond the skin, surgery alone isn’t enough. Two major categories of drug treatment have transformed outcomes for advanced melanoma over the past decade.
Immunotherapy
Immunotherapy drugs work by removing the brakes your immune system normally places on itself, allowing your body’s own defenses to recognize and attack melanoma cells. These drugs are given by IV infusion, typically every few weeks, and treatment can last a year or longer. They’re now used for both stage III melanoma (to reduce the risk of recurrence after surgery) and stage IV melanoma (to shrink or control tumors that have spread).
The tradeoff is that an unleashed immune system can attack healthy tissue too. The most common lasting side effect is an underactive thyroid, which affects roughly 1 in 10 patients and usually requires daily thyroid hormone replacement going forward. Joint inflammation, particularly arthritis, is the next most common persistent issue. Colon inflammation can occur during treatment but rarely becomes a long-term problem. Some patients develop nerve damage that causes tingling or numbness, though this sometimes resolves completely. When two immunotherapy drugs are combined, the risk of serious side effects rises significantly, from about 16% with one drug to 55% with the combination.
Targeted Therapy
About half of all melanomas carry a specific genetic mutation called BRAF. If your tumor tests positive for it, you may be eligible for targeted therapy: pills that block the signals driving cancer cell growth. These drugs are typically taken daily as oral medications rather than infusions. They often work quickly, sometimes shrinking tumors within weeks, though melanoma can eventually develop resistance. Combining two types of targeted drugs (a BRAF inhibitor and a MEK inhibitor) helps delay that resistance and is the standard approach.
Survival Rates by Stage
The numbers paint a clear picture of why early detection matters so much. Based on data from the National Cancer Institute covering 2016 through 2022:
- Localized melanoma (confined to the skin): 100% five-year relative survival
- Regional melanoma (spread to nearby lymph nodes): 76% five-year relative survival
- Distant melanoma (spread to other organs): 34% five-year relative survival
These are population averages. Individual outcomes vary based on tumor thickness, ulceration, your overall health, how well treatment works, and the specific locations where melanoma has spread. The 34% figure for distant melanoma, while sobering, has improved dramatically in recent years thanks to immunotherapy and targeted drugs. A decade ago, it was in the single digits.
Life After Treatment
Even after successful treatment, melanoma requires ongoing vigilance. People who’ve had one melanoma are at higher risk of developing a second one. Follow-up typically involves regular skin checks, with more frequent visits in the first few years when recurrence risk is highest, then gradually spacing out over time. Your doctor will examine both the original surgical site and your entire skin surface, and may also feel your lymph nodes for any changes.
Between appointments, you play a key role by monitoring your own skin. Look for new moles, changes in existing moles, or any lumps near the scar or in the area between the original melanoma and the nearest lymph nodes. Protecting your skin from UV exposure becomes especially important: this means consistent sunscreen use, protective clothing, and avoiding tanning beds entirely.
For people treated for thicker or more advanced melanomas, follow-up may also include periodic imaging scans to catch any internal recurrence early. The schedule varies by stage, but the principle is the same: the sooner a recurrence is found, the more options are available to treat it.