Subsequent studies confirmed and refined the role of depth of invasion in the prognosis of malignant melanoma.
[2][3] Currently, Breslow's depth is included in the AJCC staging guidelines for melanoma as a major prognostic factor.
Breslow's depth is measured from the granular layer of the epidermis down to the deepest point of invasion (sometimes involving detached nests of cells).
[citation needed] However, with further study, it has been shown that Clark's level has a lower predictive value, is less reproducible, and is more operator-dependent as compared with Breslow's depth.
[citation needed] Thus, in the current (2010) AJCC staging system, Clark's level has prognostic significance only in patients with very thin (Breslow depth <1 mm) melanomas.