Clark's level is a related staging system, used in conjunction with Breslow's depth, which describes the level of anatomical invasion of the melanoma in the skin.[6] Clark's level was the primary factor in earlier AJCC staging schemae for melanoma. [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.[2]