Which of the following is the single most important prognostic factor for cutaneous melanoma?

Explanation

## Breslow Thickness as the Primary Prognostic Factor **Key Point:** Breslow thickness (measured in millimeters from the granular layer of the epidermis to the deepest point of tumor invasion) is the **single most important prognostic factor** for cutaneous melanoma and is the basis for staging and treatment decisions. ### Breslow Thickness Stratification | Breslow Thickness | Stage | 5-Year Survival | Clinical Significance | |---|---|---|---| | ≤1.0 mm | IA | >95% | Thin melanoma; sentinel lymph node biopsy (SLNB) controversial | | 1.01–2.0 mm | IB | 85–90% | Intermediate; SLNB recommended | | 2.01–4.0 mm | IIA/IIB | 70–80% | Thick; SLNB recommended | | >4.0 mm | IIC | <50% | Very thick; high risk of systemic disease | **High-Yield:** Breslow thickness directly correlates with the risk of lymph node metastasis and overall survival. Every 0.1 mm increase in thickness increases the risk of sentinel node positivity. ### Why Breslow Supersedes Clark Level - **Clark level** (I–V, based on anatomic layers invaded) is less precise and has been largely replaced by Breslow thickness in modern staging - Breslow provides **quantitative, objective measurement** rather than categorical classification - Breslow is reproducible and independent of anatomic site ### Other Important Prognostic Factors (Secondary) - **Ulceration:** Presence worsens prognosis (upstages by one level) - **Mitotic rate:** ≥1 mitosis/mm² indicates worse prognosis - **Clark level:** Still used but less predictive than Breslow - **Lymphovascular invasion:** Associated with higher risk - **Tumor-infiltrating lymphocytes:** Favorable prognostic indicator **Mnemonic:** **SLIMB** — Stage, Lymph nodes, Invasion (Clark), Mitotic rate, Breslow. But Breslow is the **FIRST** and most important. **Clinical Pearl:** A 1.5 mm melanoma with ulceration is upstaged from IB to IIB due to ulceration, emphasizing that while Breslow is primary, ulceration modifies the stage and prognosis. [cite:Harrison 21e Ch 83]