AJCC 8th Edition: The standard framework for cutaneous melanoma staging and prognosis.
Primary Tumor (T)
Depth & Ulceration
Regional Nodes (N)
Lymph Node Spread
Distant Met (M)
Spread to Organs
Stage Estimate
Select the T, N, and M categories from the biopsy and pathology reports to determine the AJCC stage.
Guidelines & Evidence
Verified
Last Review: 2026-07-17
When to Use
When to Use
The AJCC 8th Edition Melanoma Staging System is applied to all patients with a confirmed histopathologic diagnosis of primary cutaneous melanoma. It drives surgical management (excision margins, sentinel lymph node biopsy eligibility), systemic therapy decisions (adjuvant immunotherapy or targeted therapy eligibility), surveillance intensity, clinical trial stratification, and prognostic counseling.
Clinical Indications
Any confirmed cutaneous melanoma ≥ 0.8 mm Breslow thickness
Melanoma < 0.8 mm with ulceration (T1b) — SLNB and adjuvant therapy discussions
Any patient with clinically suspicious lymphadenopathy after melanoma diagnosis
Post-excision pathological staging (pTNM) to determine adjuvant eligibility
Surveillance protocol intensity (Stage I vs. II vs. III vs. IV)
When NOT to Use
Ocular/uveal melanoma (different biology and staging system)
Mucosal melanoma (separate AJCC staging criteria)
Desmoplastic melanoma — special considerations for SLNB apply
Pre-biopsy (staging requires pathological tissue data)
How it Works
T Category — Primary Tumor
| TX | Thickness not assessed (e.g., shave biopsy) |
| T0 | No evidence of primary tumor (occult melanoma) |
| Tis | Melanoma in situ |
| T1a | < 0.8 mm, no ulceration |
| T1b | 0.8–1.0 mm (any), OR < 0.8 mm with ulceration |
| T2a | > 1.0–2.0 mm, no ulceration |
| T2b | > 1.0–2.0 mm, with ulceration |
| T3a | > 2.0–4.0 mm, no ulceration |
| T3b | > 2.0–4.0 mm, with ulceration |
| T4a | > 4.0 mm, no ulceration |
| T4b | > 4.0 mm, with ulceration |
N Category — Regional Lymph Nodes
N0: No regional node metastasis detected
N1a–N3c: Based on number of involved nodes AND whether involvement is microscopic (clinically occult, sentinel node) vs. macroscopic (clinically apparent)
NX Suffix: In-transit metastases, satellite lesions, and microsatellites now classified under N (N1c, N2c, N3c depending on nodal burden) — 8th edition change from 7th edition
M Category — Distant Metastasis
| M0 | No detectable distant metastasis |
| M1a(0/1) | Skin/soft tissue/non-regional nodes; LDH normal (0) or elevated (1) |
| M1b(0/1) | Lung metastasis; LDH normal (0) or elevated (1) |
| M1c(0/1) | Non-CNS visceral metastasis; LDH normal (0) or elevated (1) |
| M1d(0/1) | CNS metastasis; LDH normal (0) or elevated (1) |
Key 8th Edition Changes vs. 7th Edition
Mitotic rate is no longer used to distinguish T1a from T1b. The T1 threshold is now determined solely by thickness (0.8 mm) and ulceration. Microsatellites are now grouped with satellites/in-transit lesions under the N category. LDH sub-staging (0 vs 1) added within M1 categories.
Clinical Pearls
Guideline-Aligned Surgical Thresholds
T1a (< 0.8 mm, no ulceration): SLNB generally NOT recommended per NCCN guidelines; wide local excision with 1 cm margins.
T1b (0.8–1.0 mm OR < 0.8 mm with ulceration): SLNB offered and discussed; 1 cm excision margins.
T2–T3: SLNB strongly recommended; margins 1–2 cm depending on thickness.
T4: SLNB recommended; 2 cm margins; consider adjuvant immunotherapy (pembrolizumab, nivolumab) or targeted therapy (BRAF+MEK inhibitors if BRAF-mutant) in node-positive disease.
Limitations
Clinical staging (cTNM) is based on physical examination and imaging; pathological staging (pTNM) after SLNB and excision is more accurate and drives treatment.
The AJCC 8th edition was validated primarily in predominantly Caucasian Western cohorts; applicability to melanoma subtypes more common in darker skin (e.g., acral lentiginous) requires caution.
Survival estimates embedded in the 8th edition (from 46,906 melanoma patients) reflect outcomes from the pre-checkpoint-inhibitor era — current outcomes are likely better, particularly for Stage III–IV.
Breslow thickness is measured to the nearest 0.1 mm from the granular cell layer; shave biopsies that transect the base introduce staging uncertainty.
Adjuvant Therapy Eligibility (Post-8th Edition)
FDA-approved adjuvant therapy now available for Stage IIB/IIC (pembrolizumab, nivolumab) and Stage III (pembrolizumab, nivolumab, dabrafenib+trametinib if BRAF V600E/K). Stage IV patients with resected disease may also qualify — confirm current NCCN guidelines as evidence evolves rapidly.
Next Steps
Stage I (T1–T2a N0 M0)
01
Wide local excision with appropriate margins (1 cm for T1, 1–2 cm for T2).
02
SLNB: discuss for T1b and above; shared decision-making for T1a.
03
Surveillance: history/physical every 6–12 months × 5 years, then annually. Skin imaging as clinically indicated.
04
No adjuvant systemic therapy indicated for Stage I.
Stage II (T3–T4 N0 M0)
01
Wide local excision with 2 cm margins.
02
SLNB recommended for all Stage II patients.
03
Adjuvant pembrolizumab or nivolumab may be offered for Stage IIB/IIC per current NCCN v2.2024.
04
Baseline imaging (CT chest/abdomen/pelvis ± PET-CT) for Stage IIB/IIC.
05
Surveillance every 3–6 months × 3 years, then 6–12 monthly.
Stage III (Any T, N+, M0)
01
Complete nodal dissection (CLND) — now per NCCN only if macrometastatic disease or clinically positive nodes; CLND may be deferred for micrometastatic (SN+) disease per DeCOG-SLT/MSLT-II trial data.
02
BRAF mutation testing mandatory — affects adjuvant therapy choice.
03
Adjuvant therapy: pembrolizumab or nivolumab (all Stage III); dabrafenib+trametinib if BRAF V600E/K mutant.
04
Baseline CT and brain MRI for staging. Surveillance CT every 6 months.
Stage IV (Any T, Any N, M1)
01
Comprehensive molecular profiling: BRAF, NRAS, c-KIT, PD-L1 tumor proportion score.
02
Brain MRI mandatory. Ophthalmological evaluation if ocular symptoms.
03
First-line systemic therapy: combined nivolumab+ipilimumab, or pembrolizumab monotherapy, or BRAF+MEK inhibitors if BRAF-mutant — driven by pace of disease, LDH, and patient performance status.
04
Enroll in clinical trial where available — response rates and combinations evolving rapidly.
05
Multidisciplinary tumor board review mandatory.
The Evidence
AJCC 8th Edition Primary Reference
Melanoma staging: Evidence-based changes in the American Joint Committee on Cancer eighth edition cancer staging manual.
Gershenwald JE et al. • CA Cancer J Clin.. 2017;67(6):472–492. Analysis of 46,906 patients from AJCC Melanoma Expert Panel. Established updated TNM thresholds, microsatellite reclassification, LDH sub-staging, and removal of mitotic rate from T1 criteria.
External Links
Origins & History
The AJCC Melanoma Staging System is published by the American Joint Committee on Cancer and has undergone seven major revisions since 1977. The 8th edition (2017) was led by Dr. Jeffrey E. Gershenwald (MD Anderson Cancer Center) and Prof. Richard A. Scolyer (Royal Prince Alfred Hospital, Sydney) as co-chairs of the AJCC Melanoma Expert Panel. The 8th edition represents the most comprehensive revision of the system, analyzing outcomes from 46,906 patients across multiple international institutions. Key changes included re-anchoring the T1 threshold around ulceration rather than mitotic rate, formally reclassifying microsatellite lesions into the N category, and introducing LDH-based M1 sub-stratification.
Last Comprehensive Review: 2026-07-17