Comparative evaluation of various cytomorphological grading systems in breast carcinoma

The diagnosis of breast carcinoma can be reliably made by fine needle aspiration cytology (FNAC). Grading usually done in histological samples for the selection of therapy but not in cytology. Various cytological grading systems have been proposed; however, none of them is presently considered the gold standard to predict the prognosis.

This study was undertaken to evaluate various 3-tier cytological grading systems and to determine the best possible system corresponds to the histological grading proposed by Elston and Ellis based on the method by Nottingham modification of Scarff-Bloom-Richardson (SBR) method.

In this retrospective study, 94 cases of breast carcinoma FNACs were graded using six cytological grading systems and compared with SBR method. Concordance, association, and correlation studies were done to select best possible cytological grading system. The interobserver reproducibility among the six grading systems was also assessed.

Robinson method showed best correlation (ρ = 0.801; P = 0.0001 and τ = 0.783; P = 0.0001), maximum percent agreement (83/94 cases; 88.3%), and a substantial kappa value of agreement (κ = 0.737) with the Nottingham modification of SBR grading system followed by Mouriguand method. Taniguchi system showed better interobserver agreement (87.2%; κ = 0.738).

This study showed that all six cytological grading systems correlated positively with SBR method. However, Robinson's grading system demonstrated the best concordance, correlation, and substantial Kappa value of the agreement with the histological grading by SBR method in comparison to other 3-tier cytological grading systems. Hence, in conclusion, this grading should be routinely incorporated in the cytology reports as it correlates well with histological grade. Despite various cytological grading systems, Robinson's method is simple, more objective, and reproducible, hence being preferable for routine use.