Section V.3, Histology, Behavior, and Differentiation

V.3.5.8 Bloom-Richardson Grade for Breast Cancer

Beginning with breast cancer cases diagnosed January 1, 1996, the Bloom-Richardson grading system may be used.

Synonyms include: Modified Bloom-Richardson, Scarff-Bloom-Richardson, SBR Grading, BR Grading, Elston-Ellis modification of Bloom-Richardson grading system. This grading scheme is based on three morphologic features as follows:

  1. degree of tumor tubule formation

  2. tumor mitotic acitivity

  3. nuclear pleomorphism of tumor cells (nuclear grade)

Seven possible scores are condensed into three Bloom-Richardson grades. The three grades then translate into well-differentiated (BR low grade), moderately differentiated (BR intermediate grade) and poorly differentiated (BR high grade).

Tumor tubule formation

Score

>75% of tumor cells arranged in tubules

1

>10% and <75%

2

<10%

3

Number of mitoses

(low power scanning (X100), find most mitotically tumor area, proceed to high power (x400)

<10 mitoses in 10 high-power fields

1

>10 and <20 mitoses

2

>20 mitoses per 10 high power fields

3

Nuclear pleomorphism (nuclear grade)

Cell nuclei are uniform in size and shape, relatively small, have dispersed chromatin patterns, and are without prominent nucleoli

1

Cell nuclei are somewhat pleomorphic, have nucleoli, and are intermediate size

2

Cell nuclei are relatively large, have prominent nucleoli or multiple nucleoli, coarse chromatin patterns, and vary in size and shape

3

To obtain the final Bloom-Richardson score, add score from tubule formation plus number of mitoses score, plus score from nuclear pleomorphism. The combined score converts to the following BR grade:

Bloom-Richardson combined scores

Differentiation/BR Grade

ICD-O-3 6th digit

3, 4, 5

Well-differentiated (BR low grade)

1

6, 7

Moderately differentiated (BR intermediate grade)

2

8, 9

Poorly differentiated (BR high grade)

3

There are coding rules and conventions to be used to code breast cancer cases. Use grade or differentiation information from the breast histology in the following order:

  1. Bloom-Richardson scores 3-9

  2. Bloom-Richardson grade (low, intermediate, high)

  3. Nuclear grade

  4. Terminology (well diff, mod diff…)

  5. Histologic grade (grade I, grade ii…)

Caution : In this grading system, the terms low, intermediate, and high are codes 1, 2, and 3 respectively. This is an exception to the usual rule for all other grading systems which code "low", "intermediate", and "high" as 2, 3, and 4 respectively. In the Bloom-Richardson system, if grades 1, 2, and 3 are specified, these should be coded 1, 2, and 3 respectively.

Bloom-Richardson scores

Bloom-Richardson scores

Nuclear Grade

Terminology

Histologic Grade

Code

3- 5 points

Low Grade

1/3, 1/2

Well Differentiated

(BR low grade)

1

6, 7 points

Intermediate Grade

2/3

Moderately differentiated

(BR intermediate grade)

2

8, 9 points

High Grade

2/2, 3/3

Poorly Differentiated

(BR high grade)

3

 

SEER Program Manual entry available

COC Facility Oncology Registry Data Standards (FORDS manual) entry available