Scoring nuclear pleomorphism in breast cancer

Aims: Nuclear grade has equal weight with mitotic index and acinus formatio n in grading breast cancer, but criteria for its assessment are less well d efined. This study examines consistency of nuclear grading in breast cancer and whether improved nuclear grading criteria are required. Methods and results: Photographic prints of haematoxylin-eosin sections of 100 unselected symptomatic breast cancers were circulated to histopathologi sts who assigned each carcinoma a nuclear pleomorphism score on a linear an alogue scale 0-100 (0-33 equating to nuclear pleomorphism grade 1, 34-66 to grade 2, and 67-100 to grade 3). Seventeen histopathologists completed the exercise, including 11 breast specialists. While kappa scores for the impl ied nuclear grades indicated 'moderate' or 'good' agreement between individ uals and the group as a whole, seven pathologists allocated analogue scores significantly lower than the median score allocated by the group to each c ase, while five allocated significantly higher scores. The range was from a nalogue scores 11.3 units lower on average than the median (assigning 27% o f carcinomas nuclear grade 1, 60% grade 2, and 13% grade 3) to scores 7.5 u nits higher on average than the median (assigning only 2% carcinomas nuclea r grade 1, 46% grade 2, and 52% grade 3). Five of six non-specialists alloc ated scores significantly lower than the group medians but only two of 11 s pecialists did so (P=0.018). Conclusions: Systematic differences between pathologists in scoring nuclear pleomorphism in breast cancer potentially contribute to differences in all ocating overall grade and confirm the need for improved nuclear grading cri teria. Specialists tend to allocate higher pleomorphism scores than non-spe cialists.