Which of the following is the most important prognostic factor for cutaneous melanoma according to the AJCC staging system?

Explanation

## Breslow Thickness as Primary Prognostic Factor **Key Point:** Breslow thickness (vertical depth of tumor measured from granular layer of epidermis to deepest point of invasion) is the SINGLE MOST IMPORTANT prognostic factor in cutaneous melanoma and forms the primary basis of AJCC staging. **High-Yield:** AJCC 8th edition (2017) uses Breslow thickness as the primary determinant of T-stage, with additional modifiers (ulceration, mitotic rate) used only within specific thickness ranges. ### Breslow Thickness Stratification | Thickness | T-Stage | 5-Year Survival | |-----------|---------|----------------| | ≤1.0 mm | T1 | ~95% | | 1.01–2.0 mm | T2 | ~85–90% | | 2.01–4.0 mm | T3 | ~70–80% | | >4.0 mm | T4 | ~50–60% | **Mnemonic:** **BEAT** — **B**reslow thickness is the **E**ssential, **A**JCCCC-defined, **T**op prognostic factor. ### Why Breslow > Clark Level - Clark level (I–V based on anatomic layer) is less precise and has been de-emphasized in AJCC 8e - Breslow is objective, reproducible, and quantitative - Clark level is now used only as a secondary factor in thin melanomas (T1) ### Secondary Prognostic Modifiers - **Ulceration:** Present in T1b, T2b, T3b, T4b → worse prognosis - **Mitotic rate:** Used in T1 melanomas to distinguish T1a (0 mitoses/mm²) from T1b (≥1 mitosis/mm²) - **Lymphovascular invasion:** Adverse prognostic factor **Clinical Pearl:** A 1.5 mm melanoma with ulceration is staged T2b (higher risk) than a 1.5 mm melanoma without ulceration (T2a), demonstrating that Breslow thickness is modified by ulceration status. [cite:Harrison 21e Ch 81]