TABLE 1.
A Summary of the Major Changes Introduced and Highlights of the Eighth Edition of the AJCC Melanoma Staging Systema
| CHANGE | DETAILS OF CHANGE/HIGHLIGHT |
|---|---|
| Definition of primary tumor (T) | All principal T-category tumor thickness ranges are maintained, but T1 is now subcategorized by tumor thickness strata at 0.8-mm threshold |
| Tumor mitotic rate is removed as a staging criterion for T1 tumors: T1a melanomas are now defined as nonulcerated and <0.8 mm in thickness; T1b is now defined as melanomas 0.8–1.0 mm in thickness regardless of ulceration status OR ulcerated melanomas <0.8 mm in thickness | |
| T0 definition has been clarified: T0 should be used to designate when there is no evidence of a primary tumor or that the site of the primary tumor is unknown (eg, in a patient who presents with an axillary metastasis with no known primary tumor); staging may be based on the clinical suspicion of the primary tumor with the tumor categorized as T0 (Tis, not T0, designates melanoma in situ) | |
| Tumor thickness measurements are now recorded to the nearest 0.1 mm, not the nearest 0.01 mm, because of impracticality and imprecision of measurements, particularly for tumors >1 mm thick; tumors ≤1 mm may be measured to the nearest 0.01 mm when practical but should be reported rounded to the nearest 0.1 mm (eg, melanomas measured to be anywhere in the range from 0.75 mm to 0.84 mm are reported as 0.8 mm in thickness [and hence T1b]) | |
| Tis (melanoma in situ), T0 (no evidence of or unknown primary tumor), and TX (tumor thickness cannot be determined) may now be used as the T-category designation for stage groupings | |
| Definition of regional lymph node (N) | The number of metastasis-containing regional lymph nodes is retained |
| Previously empirically defined “microscopic” and “macroscopic” descriptors are redefined as “clinically occult” (ie, clinical stage I–II with nodal metastasis determined at sentinel node biopsy) and “clinically apparent” regional node disease (clinical stage III), respectively | |
| Sentinel node tumor burden is considered a regional disease prognostic factor that should be collected for all patents with positive sentinel nodes but is not used to determine N-category groupings | |
| Non-nodal regional disease, including microsatellites, satellites, and in-transit cutaneous and/or subcutaneous metastases, is more formally stratified by N category according to the number of tumor- involved lymph nodes (the presence of microsatellites, satellites, or in-transit metastases is now categorized as N1c, N2c, or N3c based on the number of tumor-involved, regional lymph nodes, if any) | |
| “Gross” extranodal extension no longer used as an N staging criterion (but the presence of “matted nodes” is retained) | |
| Definition of distant metastasis (M) | M1 is now defined by both anatomic site of distant metastatic disease and serum lactate dehydrogenase (LDH) value for all anatomic site subcategories |
| Descriptions of distant anatomic sites of disease are clarified in M subcategories | |
| Descriptors are now added to M1 subcategory designation that provides LDH values (designated as “0” for “not elevated” and “1” for “elevated”) for all sites of distant disease; eg, skin/soft tissue/nodal metastases with elevated LDH are now M1a(1), not M1c | |
| A new M1d designation is added to include distant metastasis to the central nervous system (CNS), with or without any other distant sites of disease; M1c no longer includes CNS metastasis | |
| Elevated LDH level no longer defines M1c | |
| AJCC prognostic stage groups | No overall change in T subcategories, but definitions of stages IA and IB are refined |
| N category is now composed of 4 substages rather than 3, and stage III subgroupings are based on multivariable models, including T-category (tumor thickness and ulceration) and N-category (number of lymph nodes, satellites/in-transits/microsatellites) elements that demonstrate a significant impact of primary tumor factors in assigning N substage | |
| Clarified that stage IV is not further substaged (ie, M1c is stage IV, not stage IVC) |
a
Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, eighth edition (2017) published by Springer International Publishing (Gershenwald JE, Scolyer RA, Hess KR, et al. Melanoma of the skin. In: Amin MB, Edge SB, Greene FL, et al, eds. AJCC Cancer Staging Manual. 8th ed. New York: Springer International Publishing; 2017:563–5854).