What are the histologic grades for breast cancer?

Updated: Feb 04, 2021
  • Author: Pavani Chalasani, MD, MPH; Chief Editor: John V Kiluk, MD, FACS  more...
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Histologic grade is the best predictor of disease prognosis in carcinoma in situ, but it is dependent on the grading system used, such as the Van Nuys classification (high-grade, low-grade comedo, low-grade noncomedo). The grading of invasive carcinoma is also important as a prognostic indicator, with higher grades indicating a worse prognosis (see Table 2 below).

Table 2. Grading System in Invasive Breast Cancer (Modified Bloom and Richardson) (Open Table in a new window)





> 2

> 3

A. Tubule formation



< 10%

B. Mitotic count/HPF (microscope- and field-dependent)

< 7



C. Nuclear size and pleomorphism

Near normal; little variation

Slightly enlarged; moderate variation

Markedly enlarged; marked variation

Grade I cancer if total score (A + B + C) is 3-5

Grade II cancer if total score (A + B + C) is 6 or 7

Grade III cancer if total score (A + B + C) is 8 or 9

HPF = high-power field.

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