The Bloom-Richardson staging system,^[1] or the modified Bloom-Richardson-Elston staging system,^[2] is a breast cancer staging system that examines the cells and tissue structure of the cancer to determine how aggressive and invasive the cancer is:^[3]

• What percent of the tumor makes normal duct structures? In cancer, there is a breakdown of the mechanisms that cells use to attach to each other and communicate with each other, to form tissues such as ducts, so the tissue structures become less orderly.
• How many mitotic figures (dividing cells) can the pathologist see in a microscope field? One of the hallmarks of cancer is that cells divide uncontrollably. The more cells that are dividing, the worse the cancer.
• Are the cell nuclei uniform like normal breast duct epithelial cells, or are they larger, irregular, and darker (pleomorphic)? In cancer, the mechanisms that control genes and chromosomes in the nucleus break down. Irregular nuclei are a sign that the mechanisms that control cell reproduction are breaking down.

Each of these features is assigned a score ranging from 1 to 3. The scores are then added together for a grade that will range between 3 to 9. This value is then used to grade the tumor as follows :

• 3-5 Grade 1 tumor (well-differentiated). Best prognosis.
• 6-7 Grade 2 tumor (moderately-differentiated). Medium prognosis.
• 8-9 Grade 3 tumor (poorly-differentiated). Worst prognosis.

Lower grade tumors, with a good prognosis, can be treated with less aggressive surgery and medication, and have a better survival rate.

Higher grade tumors must be treated with more aggressive surgery, radiation, and drugs with worse adverse effects, and have a worse survival rate.

[edit] References

1. ^ Bloom H, Richardson W (1957). "Histological grading and prognosis in breast cancer; a study of 1409 cases of which 359 have been followed for 15 years.". Br J Cancer 11 (3): 359–77. PMID 13499785. 
2. ^ PMID 9568179
3. ^ Frequently Asked Questions regarding Pathology, Breast Center at Johns Hopkins

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