StagingConceptN/A (concept)
AJCC 8 melanoma stage groups
AJCC 8th edition melanoma; AJCC v8 stage groups; melanoma pathological staging
The American Joint Committee on Cancer (AJCC) 8th edition melanoma staging system (Gershenwald et al., CA Cancer J Clin 2017) is the UK standard for melanoma staging since January 2018. It introduced major changes from AJCC 7 — most importantly the 0.8 mm Breslow cut-point for T1a vs T1b (replacing mitotic rate), the elaboration of stage III into IIIA/B/C/D subgroups by combinations of T-stage and N-stage, and the M1 sub-classification with LDH-based (0) and (1) modifiers. The system underpins UK NICE NG14 management decisions including SLNB indications, baseline imaging, adjuvant therapy eligibility (pembrolizumab TA837 for resected stage IIB/IIC, pembrolizumab TA766 or nivolumab TA684 for resected stage III, and dabrafenib + trametinib TA544 for stage III BRAF V600+), and surveillance schedules. This page provides a concept-level walkthrough of the staging logic; for interactive staging see the AJCC 8 melanoma staging tool.
CurrentLast reviewed 15 May 2026
T category
- Tis — melanoma in situ (no invasion).
- T1a — Breslow < 0.8 mm, no ulceration.
- T1b — Breslow < 0.8 mm WITH ulceration, OR 0.8–1.0 mm with or without 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.
- T0 — occult primary with regional / distant disease.
- Mitotic rate REMOVED from T1 sub-classification in AJCC 8 (was AJCC 7 criterion). Mitotic rate retained as a separate prognostic feature reported in the dataset and as a NICE NG14 SLNB trigger.
N category
- Based on number of tumour-involved nodes, clinical occultness, in-transit / satellite / microsatellite presence, and matted-node status.
- N0 — no regional nodal disease.
- N1 — 1 involved node (N1a clinically occult / N1b clinically detected) OR in-transit / satellite / microsatellite with no involved node (N1c).
- N2 — 2–3 involved nodes OR 1 involved node with in-transit / satellite / microsatellite (N2c).
- N3 — ≥ 4 involved nodes OR matted nodes OR ≥ 2 involved nodes + in-transit / satellite / microsatellite (N3c).
- Each N category has a/b/c sub-classifications based on detection mode (clinically occult = a; clinically detected = b; in-transit / satellite / microsatellite present = c).
- Microsatellites — histologically detected microscopic foci adjacent to the primary, separated by > 0.3 mm uninvolved dermis — included for the first time in AJCC 8 N classification.
M category and LDH sub-classification
- M0 — no distant metastasis.
- M1a — distant skin, soft tissue, non-regional node.
- M1b — lung.
- M1c — other visceral (non-CNS).
- M1d — CNS (new in AJCC 8; previously included in M1c).
- Each M1 sub-category modified by LDH:
- (0) — LDH normal.
- (1) — LDH elevated.
- Suffix omitted if LDH not measured.
- e.g. M1b(0) = lung metastasis with normal LDH; M1d(1) = CNS metastasis with elevated LDH.
Stage groups
- Stage 0 — Tis N0 M0 (melanoma in situ).
- Stage IA — pT1a or pT1b, N0 M0 (pathological). Note: clinical IA = cT1a only; cT1b is clinical IB. AJCC 8 (Gershenwald 2017) classifies pT1b N0 as pathological IA.
- Stage IB — pT2a N0 M0 (pathological); clinical IB = cT1b or cT2a, N0 M0.
- Stage IIA — pT2b or pT3a, N0 M0 (pathological).
- Stage IIB — pT3b or pT4a, N0 M0 (pathological).
- Stage IIC — pT4b N0 M0 (pathological).
- Stage IIIA — T1a/b–T2a with N1a or N2a, M0.
- Stage IIIB — T0 N1b/N1c; T1a/b–T2a with N1b/c or N2b; T2b/T3a with N1–N2b, M0.
- Stage IIIC — T0 N2b/c/N3b/c; T1a/b–T3a with N2c or N3; T3b/T4a any N≥N1; T4b with N1a–N2c, M0.
- Stage IIID — T4b with N3a/b/c, M0.
- Stage IV — any T, any N, M1 (any subcategory).
- Stage III is the most heterogeneous group — the AJCC 8 sub-stratification reflects substantial outcome differences between IIIA and IIID.
Major AJCC 8 changes from AJCC 7
- T1 sub-classification — now based on Breslow 0.8 mm cut-off; mitotic rate no longer T1 sub-classifier.
- Stage III sub-stratification into A/B/C/D based on T and N — substantially refined prognosis.
- M1d new category (CNS metastases) — separates from M1c visceral.
- LDH modifier — (0) / (1) added to M1 categories.
- Microsatellites incorporated into N classification (N1c, N2c, N3c).
- T0 introduced for occult primary with regional / distant disease.
- Specific 5-year survival data updated using a much larger pooled international melanoma database.
Treatment implications by stage
- Stage 0 (Tis) — at least 0.5 cm WLE; lentigo maligna and head-and-neck melanoma in situ may need wider or staged clearance. Give advice at a clinic visit in the first year, then discharge unless personalised follow-up is indicated.
- Stage IA — 1 cm WLE. Do not offer SLNB. Follow-up for 1 year.
- Stage IB — 1 cm WLE; consider SLNB only where NICE NG14 criteria apply; follow-up for 5 years.
- Stage IIA — 2 cm WLE, using 1 cm only if a 2 cm margin would cause unacceptable disfigurement or morbidity; discuss SLNB according to NICE NG14 criteria.
- Stage IIB — 2 cm WLE; discuss SLNB; consider whole-body and brain CE-CT; adjuvant pembrolizumab (TA837).
- Stage IIC — 2 cm WLE; discuss SLNB; offer whole-body and brain CE-CT; adjuvant pembrolizumab (TA837).
- Stage III — offer staging imaging; adjuvant pembrolizumab (TA766), nivolumab (TA684), or dabrafenib + trametinib (TA544 if BRAF V600+); stage III macroscopic resectable disease may be eligible for NHS England URN 2426 neoadjuvant pembrolizumab.
- Stage IV — first-line ICI (anti-PD-1 ± anti-CTLA-4); BRAF-targeted therapy for V600+; surgical metastasectomy for selected oligometastatic.
- See AJCC 8 staging tool for interactive computation and stage-specific management prompts.
References
- Gershenwald JE et al. Melanoma staging: evidence-based changes in the AJCC 8th edition. CA Cancer J Clin; 2017;67:472–92.
- Amin MB, Edge SB, Greene FL et al., eds. AJCC Cancer Staging Manual. 8th ed. New York: Springer; 2017.
- NICE NG14. Melanoma: assessment and management. London: NICE; 2015 (last updated 27 July 2022).
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