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Staging of Nonmelanoma Skin Cancer (NMSC)

Doctors use staging systems to describe how advanced a skin cancer is. Staging helps decide on treatment and gives an idea of what to expect. The two main systems are the AJCC system and the Brigham and Women’s Hospital (BWH) system.


AJCC System

Based mostly on tumor size and spread:

  • T1: Smaller than 2 cm

  • T2: Between 2–4 cm

  • T3: Larger than 4 cm or growing into nerves or bone nearby

  • T4: Deep growth into bone or bone marrow

BWH System

Based on risk factors that make the cancer more serious:

  • T1: No risk factors

  • T2a: 1 risk factor

  • T2b: 2–3 risk factors

  • T3: 4 or more risk factors, or bone invasion

Risk factors include:

  • Tumor larger than 2 cm

  • Poorly differentiated (looks more abnormal under the microscope)

  • Grown into nerves

  • Spread deep under the skin

What This Means

  • Lower stages = smaller, less risky cancers

  • Higher stages = bigger, deeper, or more aggressive cancers

  • Staging helps doctors choose the safest and most effective treatment



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