Application of the Scarff-Bloom-Richardson tumor grading system to fine-needle aspirates of the breast.

Assigning a tumor grade to breast cancers provides important prognostic information. This study evaluated the applicability of the Scarff-Bloom-Richardson (SBR) breast cancer grading system to aspiration biopsy cytology. Thirty-five consecutive breast cancer fine-needle aspirates and their surgical specimens were reviewed by two pathologists. An SBR grade of 1-3 was assigned by each pathologist to both the fine-needle aspirate and biopsy specimen, based on the sum of scores given to each of three features: tubular differentiation, nuclear pleomorphism, and mitotic index. Both pathologists assigned the same SBR score to 74.3% of biopsy specimens and 65.7% of fine-needle aspirates. The cytologic grade could be used to predict the histologic grade in as many as 57.1% of cases. The wide disparities in the cytologic and histologic grades in some cases were chiefly due to difficulties in detecting mitoses or tubules in the cytology.