# Breslow thickness

Source: https://onco.cc/terms/breslow-thickness/  
OnCo record `breslow-thickness` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

How deep a melanoma has grown into the skin, in millimetres. The single strongest predictor of whether it will spread.

## Summary

Breslow thickness is the depth in millimetres to which a melanoma has grown into the skin, measured from the granular layer to the deepest tumour cell, and it is the single strongest predictor of whether the cancer will spread. It drives the T stage within TNM staging, from T1 for lesions of 1 mm or less to T4 for those over 4 mm, and it determines when a sentinel lymph node biopsy is offered, generally from around 0.8 mm or when ulceration is present. Together with ulceration, which upstages within each thickness band, it sets eligibility for adjuvant therapy. Readers meet it on the melanoma page, in the wide local excision entry, and in the dermoscopy, total-body photography and AI skin analysis technology.

## Fields

- Kind: Term
- Last checked: 2026-09-07

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Breslow%27s_depth
- Wikipedia: https://en.wikipedia.org/wiki/Breslow%27s_depth

## Connected records

- cancers: [Acral melanoma](https://onco.cc/cancers/acral-melanoma/), [Melanoma](https://onco.cc/cancers/melanoma/), [Stage IIB and IIC melanoma](https://onco.cc/cancers/stage-ii-melanoma/), [Stage III melanoma (after surgery)](https://onco.cc/cancers/stage-iii-melanoma/)
- terms: [Depth of invasion (DOI)](https://onco.cc/terms/depth-of-invasion/), [TNM staging](https://onco.cc/terms/tnm-staging/), [Ulceration (melanoma)](https://onco.cc/terms/ulceration-melanoma/), [Wide local excision](https://onco.cc/terms/wide-local-excision/)
- technologies: [Dermoscopy, total-body photography & AI skin analysis](https://onco.cc/technologies/dermoscopy-ai/)

---
JSON: https://onco.cc/api/v1/entities/breslow-thickness.json