Key to graph
Breslow depths are shown in millimeters next to the corresponding lines and are colour coded
Solid Line denotes non ulcerated survival curve
Dotted Line denotes ulcerated tumour survival time for the same (coloured) Breslow depth
Tumours of greater Breslow depth are more likely to invade lymphatic or blood vessels allowing a route of passage for distant spread. Survival is accordingly shorter in such cases.
Ulceration is equivalent to having a thicker, more advanced tumour
A tumour of the same Breslow depth which ulcerates the skin under which it lies is likely to be aggressive and therefore behaves like a tumour of a greater depth. The graph demonstrates that ulceration can be said to almost increase the Breslow thickness by one category in the study shown.
Balch et al. Prognostic Factors Analysis of 17,600 Melanoma Patients: Validation of the American Joint Committee on Cancer Melanoma Staging System. Journal of Clinical Oncology, Vol 19, Issue 16 (August), 2001: 3622-3634