Melanoma Stages: How Melanoma Is Classified and What Each Stage Means
Written by North Editorial Staff | Clinically reviewed by Laura Morrissey, RN, BSN | Last reviewed: March 2026
Key Takeaways
Melanoma is staged using the TNM staging system, Tumor, Nodes, Metastasis, on a scale from Stage 0 to Stage IV.
Breslow thickness (how deeply the tumor has grown into the skin) is one of the strongest predictors of outcome and drives early staging decisions.
Stages 0 through II represent localized disease; Stage III means regional lymph node involvement; Stage IV means the cancer has spread to distant organs.
For Stage IV metastatic melanoma, the 5-year survival rate has risen from under 10% before 2011 to approximately 35% or more today, thanks largely to immunotherapy and BRAF mutation-targeted drugs.
Your stage is a starting point for treatment planning, it is not a fixed destiny. Many people with advanced melanoma respond meaningfully to current treatments.
How Is Melanoma Staged?
Melanoma is staged using the TNM system: T describes tumor thickness and characteristics, N describes spread to nearby lymph nodes, and M describes distant metastasis. Stages range from 0 (cancer cells confined to the surface layer) through IV (spread to distant organs). Breslow thickness: how deeply the tumor penetrates the skin, is the single most important factor in early staging.
Stage 0: Melanoma In Situ
Stage 0 melanoma, also called melanoma in situ, means that abnormal melanocytes are present only in the outermost layer of the skin (the epidermis) and have not grown into the deeper layers. The cells are cancerous in character but have not yet invaded surrounding tissue.
Lentigo maligna is one of the most common forms of melanoma in situ. It typically appears as a flat, irregularly shaped, tan-to-brown patch on chronically sun-damaged skin, most often on the face or neck of older adults. Lentigo maligna can remain in situ for years before progressing to invasive lentigo maligna melanoma.
Stage 0 melanoma is highly curable. The standard treatment is surgical excision with appropriate margins, and the 5-year survival rate is essentially 100% when fully removed. Follow-up monitoring is still recommended because patients with a history of melanoma have an elevated risk of developing a second primary melanoma.
Stage I: Early Localized Melanoma
Stage I melanoma is invasive, it has grown through the epidermis into the dermis, but it remains confined to the original site. No lymph node involvement or distant spread is present. Stage I is divided into two substages.
Stage IA describes a melanoma that is 1 mm or less in Breslow thickness with no ulceration (breakdown of the skin surface over the tumor) and a mitotic rate of less than 1 per square millimeter. Stage IA tumors carry an excellent prognosis.
Stage IB describes melanomas that are either 1 mm or less with ulceration, or between 1 mm and 2 mm without ulceration. The 5-year relative survival rate for Stage I melanoma overall is approximately 98–99%, though this varies slightly by substage.
Treatment at this stage is primarily surgical, wide local excision to remove the tumor with adequate margins. A sentinel lymph node biopsy is often recommended for tumors thicker than 0.8 mm to determine whether cancer cells have spread to the nearest draining lymph nodes, which informs staging and prognosis even when results are negative.
Stage II: Thicker Localized Melanoma
Stage II melanoma is still localized, no lymph node involvement has been detected, but the tumor is thicker or has features (ulceration) that place it at higher risk of spread. Stage II is divided into three substages.
Stage IIA includes melanomas 1–2 mm thick with ulceration, or 2–4 mm thick without ulceration.
Stage IIB includes melanomas 2–4 mm thick with ulceration, or greater than 4 mm without ulceration.
Stage IIC describes melanomas greater than 4 mm thick with ulceration. Stage IIC carries a worse prognosis than some Stage IIIA tumors, a fact that has driven research into adjuvant (post-surgical) therapies for this substage.
The 5-year survival rate for Stage II melanoma ranges roughly from 82% (Stage IIA) to about 53% (Stage IIC), though data vary by source and treatment era.
Adjuvant therapy is now an important consideration for Stage IIB and IIC. Pembrolizumab (immunotherapy) received FDA approval for adjuvant use in resected Stage IIB and IIC melanoma based on evidence of improved recurrence-free survival. If you are in this substage, discussing adjuvant treatment with your oncologist is important.
Stage III: Regional Spread
Stage III means melanoma has spread to regional lymph nodes, nearby skin (satellite lesions), or lymphatic channels (in-transit metastases). This is a significant step in staging because it confirms that the cancer has moved beyond the primary site. Stage III is divided into substages IIIA through IIID, with IIID representing the most extensive regional spread.
Stage IIIA involves microscopic spread to one to three lymph nodes from a thin, non-ulcerated primary tumor, and carries a relatively favorable prognosis for Stage III disease (5-year survival approximately 78%).
Stage IIIB, IIIC, and IIID represent progressively more extensive regional involvement: more lymph nodes, ulceration at the primary site, in-transit or satellite lesions, or combinations of these factors. Five-year survival estimates range roughly from 40% to 68% across these substages.
Surgery to remove the primary tumor and affected lymph nodes remains the foundation of Stage III treatment. Critically, adjuvant therapy: immunotherapy or targeted therapy given after surgery to reduce the risk of recurrence, is now the standard of care for resected Stage III melanoma. Options include:
Checkpoint inhibitor therapies such as pembrolizumab and nivolumab (PD-1 inhibitors)
Ipilimumab (a CTLA-4 inhibitor) in combination with nivolumab for some patients
BRAF/MEK inhibitor combinations (dabrafenib + trametinib) for patients whose tumors carry a BRAF mutation
These adjuvant treatments have significantly improved recurrence-free survival in Stage III melanoma compared to surgery alone.
Stage IV: Metastatic Melanoma
Stage IV metastatic melanoma means the cancer has spread to distant sites, lymph nodes far from the primary tumor, other organs, or both. Stage IV is subcategorized based on where the cancer has spread:
M1a: Distant skin, subcutaneous tissue, or distant lymph nodes; normal LDH (lactate dehydrogenase)
M1b: Lung metastases; normal LDH
M1c: Any other distant organ metastases; normal LDH
M1d: Brain or spinal cord metastases; any LDH level
Historically, Stage IV melanoma carried a median survival of under 9 months and a 5-year survival rate in the range of 5–10%. That picture has changed profoundly.
The approval of ipilimumab in 2011 was the first treatment in decades to improve overall survival in metastatic melanoma. It was followed by pembrolizumab and nivolumab, BRAF/MEK inhibitor combinations, and the combination of nivolumab plus ipilimumab, which together have raised the 5-year survival rate for Stage IV melanoma to approximately 35% or more in clinical trial populations. Long-term survival, previously almost unheard of, is now a realistic goal for a meaningful proportion of patients with metastatic disease.
If you have been diagnosed with Stage IV melanoma, the most important next steps are molecular testing to identify your tumor’s genomic features (particularly BRAF mutation status), evaluation at a center with experience in melanoma, and a thorough conversation about both approved treatments and clinical trial options. This is a stage where access to the most current treatments, including trials of emerging therapies, can be meaningfully life-extending.
Breslow Thickness and Other Prognostic Factors
Breslow thickness is the measurement, in millimeters, of how deeply a melanoma has grown from the outermost layer of the epidermis downward into the skin. It is measured by a pathologist examining the biopsy specimen under a microscope and is reported on your pathology report.
Breslow depth is one of the most powerful independent predictors of outcome in melanoma:
Tumors 1 mm or less in thickness have an excellent prognosis
Tumors between 1 and 2 mm carry intermediate risk
Tumors greater than 4 mm carry significantly higher risk of regional and distant spread
Several other factors also influence prognosis:
Ulceration: the absence of an intact epidermis over the tumor, is a sign of more biologically aggressive disease and shifts patients to a higher substage regardless of thickness.
Mitotic rate (the number of actively dividing cells per square millimeter of tumor) is another marker of tumor aggressiveness. A higher mitotic rate is associated with worse outcomes and influences staging decisions for thin melanomas.
Lymph node status: whether cancer cells have reached nearby lymph nodes, and how many, is the dominant factor in distinguishing Stage II from Stage III.
Site of metastasis in Stage IV disease affects both prognosis and treatment planning. Brain metastases (M1d) carry particular implications for management.
LDH (lactate dehydrogenase) level in the blood is incorporated into Stage IV substaging. Elevated LDH has historically been associated with a worse prognosis in metastatic melanoma.
What Your Stage Means for Treatment
Staging is the foundation on which your treatment plan is built, but it is a starting point, not a ceiling.
For early-stage melanoma (Stages 0–IIA), surgery is often the primary and potentially only treatment needed, with close surveillance afterward. For higher-risk early-stage disease (IIB, IIC), adjuvant immunotherapy is now an established option to reduce recurrence risk. For Stage III, adjuvant therapy after surgery has become standard of care. For Stage IV, a combination of immunotherapy, targeted therapy, or clinical trials now offers many patients meaningful disease control and, for some, long-term remission.
The specific treatment your team recommends will depend on your stage, substage, BRAF mutation status, overall health, prior treatments, and personal preferences. Understanding your stage empowers you to ask the right questions and participate actively in those decisions.
For more on what each treatment involves, see our article on melanoma treatment. For data on outcomes by stage, see melanoma survival rates.
If you or someone you love has been diagnosed with melanoma, clinical trials may offer access to the latest treatments. Start your search at North’s trial finder.
Frequently Asked Questions
What stage of melanoma is curable?
Melanoma in Stages 0, I, and II is generally highly curable with surgical treatment, with 5-year survival rates ranging from approximately 82% to nearly 100% depending on substage. Stage III melanoma, while more serious, is treated with curative intent in many patients, and long-term remission is achievable. Even Stage IV melanoma is no longer uniformly fatal, a meaningful proportion of patients on modern immunotherapy regimens achieve long-term disease control, and some appear to be long-term survivors, though cure in the traditional sense is less predictable.
What is the difference between Stage III and Stage IV melanoma?
Stage III melanoma has spread to regional lymph nodes, nearby skin, or lymphatic channels, but has not reached distant organs. Stage IV melanoma has spread to distant sites, such as the lungs, liver, brain, or bones. This distinction matters enormously for treatment: Stage III is treated with surgery plus adjuvant therapy with curative intent, while Stage IV treatment focuses on controlling systemic disease with immunotherapy, targeted therapy, or clinical trials, with a goal of long-term disease control or remission.
What does Breslow thickness mean?
Breslow thickness is the depth of the melanoma tumor measured in millimeters from the surface of the skin downward, as determined from the biopsy specimen under a microscope. It is one of the single most important factors in staging and prognosis. Thinner tumors (under 1 mm) carry an excellent prognosis; thicker tumors (over 4 mm) are associated with a higher risk of lymph node spread and recurrence. Your pathology report will include this measurement.
How is melanoma staged after biopsy?
After biopsy confirms a melanoma diagnosis, your pathology report will include features like Breslow thickness, ulceration, and mitotic rate, these determine the T (tumor) category in the TNM system. Your doctor will then likely recommend a sentinel lymph node biopsy (for tumors thicker than about 0.8 mm) to assess lymph node involvement. Imaging tests such as CT, PET, or MRI may be ordered to look for distant spread if there is reason to suspect it. Together, these results determine your clinical and pathologic stage.
Has Stage IV melanoma survival improved?
Yes, dramatically. Before 2011, the median survival for Stage IV melanoma was under 9 months and the 5-year survival rate was approximately 5–10%. Following the approval of ipilimumab in 2011, and then pembrolizumab, nivolumab, and BRAF/MEK-targeted therapies, the treatment landscape transformed. Long-term follow-up data from major clinical trials now show 5-year survival rates of 35% or more for patients on combination immunotherapy, and a subset of patients appear to achieve durable, long-term remission. For patients whose tumors harbor a BRAF mutation, targeted therapy provides additional options. Research continues, and melanoma clinical trials are actively studying the next generation of treatments.
References
National Cancer Institute. Melanoma Treatment (PDQ), Patient Version. https://cancer.gov/types/skin/patient/melanoma-treatment-pdq
National Cancer Institute SEER Program. Cancer Stat Facts: Melanoma of the Skin. https://seer.cancer.gov/statfacts/html/melan.html
American Cancer Society. Melanoma Skin Cancer Stages. https://www.cancer.org/cancer/types/melanoma-skin-cancer/detection-diagnosis-staging/melanoma-skin-cancer-stages.html
Eggermont AMM, Blank CU, Mandala M, et al. Adjuvant pembrolizumab versus placebo in resected stage III melanoma. N Engl J Med. 2018;378(19):1789-1801. https://pubmed.ncbi.nlm.nih.gov/29658430.
Luke JJ, Rutkowski P, Queirolo P, et al. Pembrolizumab versus placebo as adjuvant therapy in completely resected stage IIB or IIC melanoma (KEYNOTE-716). Lancet. 2022;399(10336):1718-1729. https://pubmed.ncbi.nlm.nih.gov/35367007
Larkin J, Chiarion-Sileni V, Gonzalez R, et al. Five-year survival with combined nivolumab and ipilimumab in advanced melanoma. N Engl J Med. 2019;381(16):1535-1546. https://pubmed.ncbi.nlm.nih.gov/31562797.