Within the last decade, histologic grading has become widely accepted as a powerful indicator of prognosis in breast cancer. The majority of tumor grading systems currently employed for breast cancer combine nuclear grade, tubule formation and mitotic rate. In general, each element is given a score of 1 to 3 (1 being the best and 3 the worst) and the score of all three components are added together to give the "grade" (1-4).
Until recently, the most common grading systems used in the United States were the original Scarff-Bloom-Richardson (SBR) system as described above and the Black method which emphasizes nuclear grading and excludes consideration of tubules as a criteria (9). In Europe, the Elston-Ellis modification of the SBR grading system (Nottingham grading system) is preferred and is becoming increasingly popular in the US (7). This modification provides somewhat more objective criteria for the three component elements of grading and specifically addresses mitosis counting in a more rigorous fashion (4). For example hyperchromatic nuclei and apoptotic cells which are counted in the original SBR system are excluded in the Elston-Ellis modification and the area being assessed is specifically defined in square millimeters. These modifications have enhanced reproducibility of grading among pathologists and to a considerable extent have fostered acceptance of grading by clinicians (7,10-20). An excellent historical discussion of grading systems can be found in Elston and Ellis (17).
Criteria for grading are an active area of investigation particularly in regards to defining more objective criteria for assessing nuclear grade and we should expect image analysis to greatly contribute to this area in the future. The beginner is encouraged to consult their local pathologist to determine which system is used in their institution. The examples provided here, by Dr. Hanne Jensen, illustrate how the Nottingham Grading System can be used to grade a tumor.
When, on my pathology report, I read "modified Bloom-Richardson Histologic Grade" -- I wonder if this is the Nottingham Modification.
I will ask!