Pathologists' agreement with experts and reproducibility of breast ductal carcinoma-in-situ classification schemes

Several histologic classifications for breast ductal carcinoma in situ (DCI S) have been proposed. This study assessed the diagnostic agreement and rep roducibility of three DCIS classifications (Holland [HL], modified Lagios [ LA], and Van Nuys [VN]) by comparing the interpretations of pathologists wi thout expertise in boast pathology with those of three breast pathology exp erts, each a proponent of one classification. Seven nonexpert pathologists in New Hampshire and three experts evaluated 40 slides of DCIS according to the three classifications. Twenty slides were reinterpnted by each nonexpe rt pathologist. Diagnostic accuracy (nonexperts compared with experts) and reproducibility were evaluated using inter- and intrarater techniques (kapp a statistic). Final DCIS grade and nuclear grade were reported most accurat ely among nonexpert pathologists using HL (kappa = 0.53 and 0.49, respectiv ely) compared with LA and VN (kappa = 0.29 and 0.35, respectively, for both classifications). An intermediate DCIS grade was assessed most accurately using HL and LA, and a high grade (group 3) was assessed most accurately us ing VN. Diagnostic reproducibility was highest using HL (kappa = 0.49). The VN interpretation of necrosis (present or absent) was reported more accura tely than the LA criteria (extensive, focal, or absent; kappa = 0.59 and 0, 45, respectively), but reproducibility of each was comparable (kappa = 0.48 and 0.46, respectively). Intrarater agreement was high overall. Comparing all three classifications, final DCIS grade was reported best using HL. Nuc lear grade (cytodifferentiation) using HL and the presence or absence of ne crosis were the criteria diagnosed most accurately and reproducibly. Establ ishing one internationally approved set of interpretive definitions, with a cceptable accuracy and reproducibility among both pathologists with and wit hout expertise in breast pathology interpretation, will assist researchers in evaluating treatment effectiveness and characterizing the natural histor y of DCIS breast lesions.