Melanoma staging: Evidence-based changes in the American Joint Committee on Cancer eighth edition cancer staging manual

Abstract

Answer questions and earn CME/CNE To update the melanoma staging system of the American Joint Committee on Cancer (AJCC) a large database was assembled comprising >46,000 patients from 10 centers worldwide with stages I, II, and III melanoma diagnosed since 1998. Based on analyses of this new database, the existing seventh edition AJCC stage IV database, and contemporary clinical trial data, the AJCC Melanoma Expert Panel introduced several important changes to the Tumor, Nodes, Metastasis (TNM) classification and stage grouping criteria. Key changes in the eighth edition AJCC Cancer Staging Manual include: 1) tumor thickness measurements to be recorded to the nearest 0.1 mm, not 0.01 mm; 2) definitions of T1a and T1b are revised (T1a, <0.8 mm without ulceration; T1b, 0.8-1.0 mm with or without ulceration or <0.8 mm with ulceration), with mitotic rate no longer a T category criterion; 3) pathological (but not clinical) stage IA is revised to include T1b N0 M0 (formerly pathologic stage IB); 4) the N category descriptors "microscopic" and "macroscopic" for regional node metastasis are redefined as "clinically occult" and "clinically apparent"; 5) prognostic stage III groupings are based on N category criteria and T category criteria (ie, primary tumor thickness and ulceration) and increased from 3 to 4 subgroups (stages IIIA-IIID); 6) definitions of N subcategories are revised, with the presence of microsatellites, satellites, or in-transit metastases now categorized as N1c, N2c, or N3c based on the number of tumor-involved regional lymph nodes, if any; 7) descriptors are added to each M1 subcategory designation for lactate dehydrogenase (LDH) level (LDH elevation no longer upstages to M1c); and 8) a new M1d designation is added for central nervous system metastases. This evidence-based revision of the AJCC melanoma staging system will guide patient treatment, provide better prognostic estimates, and refine stratification of patients entering clinical trials. CA Cancer J Clin 2017;67:472-492. © 2017 American Cancer Society.

Keywords: American Joint Committee on Cancer (AJCC); TNM classification; melanoma; metastasis; pathology; prognosis; staging; survival.

FIGURE 1

Kaplan-Meier Melanoma-Specific Survival Curves According to T Subcategory for Patients With Stage I and II Melanoma From the Eighth Edition International Melanoma Database. Patients with N0 melanoma have been filtered, so that patients with T2 to T4 melanoma were included only if they had negative sentinel lymph nodes, whereas those with T1N0 melanoma were included regardless of whether they underwent sentinel lymph node biopsy.

FIGURE 2

Kaplan-Meier Melanoma-Specific Survival Curves According to Mitotic Rate (Mitoses per mm²) in Patients With Stage I and II Melanoma From the Eighth Edition International Melanoma Database.

FIGURE 3

Kaplan-Meier Melanoma-Specific Survival Curves According to (A) N Categories and (B) Subcategories From the Eighth Edition International Melanoma Database.

FIGURE 4

Kaplan-Meier Melanoma-Specific Survival Curves According to the Presence or Absence of Microsatellites, Satellites, and/or In-Transit Metastases From the Eighth Edition International Melanoma Database. Note that in-transit in the figure means in-transit and/or satellite metastasis and both means microsatellites and in-transit and/or satellite metastasis.

FIGURE 5

Kaplan-Meier Melanoma-Specific Survival Curves According to Stage in Patients With Stage I to III Melanoma From the Eighth Edition International Melanoma Database.

FIGURE 6

Kaplan-Meier Melanoma-Specific Survival Curves According to T Category Stage Group for Patients With Stage I and II Melanoma From the Eighth Edition International Melanoma Database. Patients with N0 melanoma were filtered, so that patients with T2+ melanoma were included only if they had negative sentinel lymph nodes, whereas those with T1N0 melanoma were included regardless of whether they underwent sentinel lymph node biopsy.

FIGURE 7

Kaplan-Meier Melanoma-Specific Survival Curves According to Stage III Subgroups From the Eighth Edition International Melanoma Database.

FIGURE 8

American Joint Committee on Cancer (AJCC) Eighth Edition Stage III Subgroups Based on T and N Categories.

FIGURE 9

Kaplan-Meier Melanoma-Specific Survival Curves According to Maximum Dimension of Sentinel Lymph Node Metastatic Focus (mm) From the Eighth Edition International Melanoma Database. Note that there were insufficient data (<10 cases) to estimate 10-year melanoma-specific survival for patients who had a maximum sentinel lymph node metastatic focus of 2 to 4 mm.