New TNM melanoma staging system: linking biology and natural history to clinical outcomes.

The American Joint Committee on Cancer (AJCC) implemented major revisions of the melanoma TNM and stage grouping criteria in the recently published 6th edition of the Staging Manual. The new staging system better reflects independent prognostic factors that are used in clinical trials and in reporting the outcomes of various melanoma treatment modalities. Major revisions include: 1) melanoma thickness and ulceration but not level of invasion to be used in the T classification, 2) the number of metastatic lymph nodes rather than their gross dimensions and the delineation of microscopic vs. macroscopic nodal metastases to be used in the N classification, 3) the site of distant metastases and the presence of elevated serum lactic dehydrogenase (LDH) to be used in the M classification, 4) an upstaging of all patients with Stage I, II, and III disease when a primary melanoma is ulcerated, 5) a merging of satellite metastases around a primary melanoma and in transit metastases into a single staging entity that is grouped into Stage III disease, and 6) a new convention for defining clinical and pathological staging so as to take into account the new staging information gained from intraoperative lymphatic mapping and sentinel node biopsy.