Skin Cancer Stages Explained: From Stage 0 to Stage 4

Skin cancer stages are how dermatologists and oncologists translate “we found melanoma” into “here’s exactly how far it’s gone and what we need to do about it.” Two people can both hear that same diagnosis in the same week and walk away with very different outlooks and treatment plans, and the difference almost always comes down to stage. Understanding what each of the skin cancer stages actually means makes a diagnosis feel less like an abstract scare and more like a specific, actionable situation.This guide focuses on the skin cancer stages used for melanoma specifically, since it’s the form staged this way most often and the one where stage has the biggest impact on outlook. Basal cell and squamous cell carcinoma are staged too, but they’re rarely discussed in these terms since the vast majority are caught and treated well before advanced staging becomes relevant.How Skin Cancer Stages Are DeterminedMelanoma staging uses what’s called the TNM system, developed by the American Joint Committee on Cancer (AJCC):T (Tumor): How deep the melanoma has grown into the skin, measured in millimeters. This measurement is called the Breslow depth, and it’s one of the strongest predictors of ...