Breast cancer grading

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Breast cancer grading is useful prognosticator. It is done routinely on all invasive breast cancers.

The most common is the Nottingham system, also known as Scarff-Bloom-Richardson.

Nottingham grade and Nottingham score redirect here.

Nottingham system

Nottingham is based on:

  1. Nuclear grade.
    • Small, regular (1.5-2x RBC dia.) = 1.
    • Moderated variability = 2.
    • Marked variation (>2.5x RBC dia.) = 3.
  2. Tubule formation.
    • Majority of tumour - tubules >75% = 1.
    • Moderate - 10% to 75% = 2.
    • Minimal <10% = 3.
  3. Mitotic rate.
    • 0-5 mitosis/10 HPF (1.52 mm2 --or-- 0.0152 mm2 * 10) = 1.
    • 6-10 mitosis/10 HPF (1.52 mm2) = 2.
    • >11 mitosis/10 HPF (1.52 mm2) = 3.

Mnemonic: TMN = tubule formation, mitotic rate, nuclear grade.

Notes:

  • Elston & Ellis devised the system that is used.[1] They also wrote a follow-up article in 2002.[2]

Note about mitosis counting

  • One really ought to adjust for the size of the field of view.
  • Most of modern microscopes have an eye piece diameter of 22 mm. Therefore, the field diameter at 40x is approximately 22 mm / 40x ~= 0.55 mm and the field of view is pi/4*(0.55 mm)2 = 0.2376 mm2.
    • Thus, on a typical modern microscope (with a FOV of 0.2376 mm2) one should sample 6 or 7 fields of view (FsOV).
      • Calculation: 1.52 mm2 (sampling area) / 0.2376 mm2 (area / FOV ) = 6.40 FsOV.

STATISTICAL NOTE: Sampling 10 high power fields, where the field of view (FOV) is 0.152 mm2, is not the same as sampling ten fields, where the FOV is 0.312 mm2. It surprising that Elston & Ellis ignore the fact that "10 HPFs" on different microscopes represent different sample areas and that they do not standardize the sampling area.

Calculating Nottingham score

  • Grade I = 3-5 points.
  • Grade II = 6-7 points.
  • Grade III = 8-9 points.

Notes:

  • Most tumours are grade II.
  • The mitotic score is most often 1/3.
  • The nuclear score is rarely 1/3 -- even in the tubular subtype.[3]

See also

References

  1. Elston CW, Ellis IO (November 1991). "Pathological prognostic factors in breast cancer. I. The value of histological grade in breast cancer: experience from a large study with long-term follow-up". Histopathology 19 (5): 403–10. PMID 1757079.
  2. Elston CW, Ellis IO (September 2002). "Pathological prognostic factors in breast cancer. I. The value of histological grade in breast cancer: experience from a large study with long-term follow-up. C. W. Elston & I. O. Ellis. Histopathology 1991; 19; 403-410". Histopathology 41 (3A): 151–2, discussion 152–3. PMID 12405945.
  3. MUA. 20 January 2009.