The histological workup for breast cancer diagnosis and treatment
The histological workup is the summary report of the pathologist. Essentially, breast cancer histology evaluation is the microscopic analysis of the chemical and cellular properties of the cells of a suspicious breast tumor.
The pathologist will also confirm the size of the breast tumor where necessary for breast cancer staging purposes. So, breast cancer histology is essential to determine the most effective approaches to hormone and chemotherapy treatments when necessary.
This page is still great for research material and I would still use it, however it is getting somewhat old… So I have a newer version of this page with more up-to-date information on Breast Cancer Diagnosis and Treatment.
But What is Breast Cancer Histology?
Histology is basically the microscopic study of living tissues. There are really four basic types of tissue in the body:-
- epithelial tissue
- muscle tissue
- connective tissue
- nervous tissue
Breast cancer (breast carcinoma) is a malignant transformation of epithelial tissue (usually glandular tissue). Fat (adipose) and fibrous tissue are both ‘connective’ tissues, which may also form into suspicious lesions on mammography.
However, breast cancer histology can almost always confirm the exact nature of a tumor or lesion.
How are Samples taken for Breast Cancer Histology
Firstly, a suspicious breast lesion appears on mammogram or ultrasound. Secondly a specialist will take a biopsy sample from the lesion and send it for a breast cancer histology evaluation by the pathologist.
There are different types of biopsy available and these obtain varying amounts of tissues. The types of biopsy are:-
- fine needle biopsy
- core biopsy
- excisional biopsy
However, generally, one tries to remove as little tissue as possible while remaining confident that the sample is representative and taken from the right spot.
So, an initial biopsy sampling and analysis, is in some way, an extension of the breast cancer screening process and can confirm whether breast cancer is positive or negative. (Sometimes the lesion appears to be ‘at risk‘ for breast cancer, but is not yet malignant, resulting in a follow-up screening in a few months).
Staging of Breast Cancer
Once the pathologist confirms a breast cancer, the staging process begins. At that time, an additional sample of breast tissue may be necessary for more extensive histological evaluation. In addition, examination of the lymph nodes may also be necessary.
In the image below breast carcinoma has metastasized to the lymph nodes. The ‘dark‘ cells are nodes, while the purplish ‘duct-forming’ areas are breast cancer.
Histological grade of breast cancer
The pathologist will be able to tell if the breast cancer is still confined to the breast ducts, (DCIS), or whether it is at the infiltrative or invasive status. Also, your breast cancer specialist will determine whether or not the cancer has metastasized to the lymph nodes in the axilla based on an additional sample from that region. However, a PET scan can also be useful to determine this.
The cancer stage is largely a function of the invasive or non-invasive status of the breast cancer. The grade of the breast cancer is related more to the actual microscopic character of the cells in the breast tumor.
Based on a variety of cellular features, the histological analysis helps determine the type of breast cancer (unless it is a generic or NOS type cancer) and the grade.
So, histological classification of breast cancer into essentially grades I, II, and III, determines the urgency and aggressiveness of treatment. This is because the higher grades do tend to correspond to poorer survival rates and prognosis.
The Pathologist’s Role in Breast Cancer Histology
What the pathologist will be considering is the:-
- degree of tubule formation within the tumor, i.e. the number and differentiation of tubule
- mitotic count, i.e. the rate and number of cell divisions
- nuclear pleomorphism. Basically the appearance of the cells and cell nuclei in increasing amounts of variation and bizarre randomness
The score is a combination from the three observations and determines the histological grade of the breast cancer. Statistically, the five year survival rate for grade I breast cancers over 80%.
The prognosis for grade II and III breast cancers is somewhat less optimistic, with five year survival rates of about 64% and 50% respectively. The pathologist may also note the presence and amount of necrosis (cell and tissue death and decay) and calcifications. Necrosis tends to be another indicator of an aggressive breast cancer.
Oncologists have used the presence of steroid receptors to predict breast cancer outcome and responsiveness to therapy for many years now. The usual method for measuring the presence of steroid receptors in breast cancer tumors is now by immunohistochemistry. There are no hard-and-fast rules for how to interpret the presence of various hormone and hormone receptor levels, but certain generally tendencies can be observed.
Estrogen and Progesterone receptors
The most important hormonal indicators to identify are the positive presence of estrogen and progesterone receptors. Breast cancers which over express high amounts of estrogen and progesterone receptors are likely to be more responsive to endocrine therapy treatment.
Estrogen and progesterone receptors levels are detected in the nucleus of malignant cancer cells only, by the application of a protein-based stain.
HER-2; human epidermal growth factor receptor 2
Human epidermal growth factor receptor 2 (or HER2, or Her-2/neu/c-erb B2) has been an important aspect of breast cancer histology since about 1987.
It has been shown that high levels of either HER2 gene amplification or protein expression tends to result in a poorer breast cancer prognosis. A monoclonal antibody therapy was developed to counter the effects of HER2, (trastuzumab), and its use has been shown to reduce rates of recurrence and mortality in HER2 postie early stage breast cancers.
In the image above, the brown stain is attaching to HER-2 receptors, which would indicate a fairly positive result for HER-2/neu. Consequently, treatment for this particular breast cancer would likely benefit from the use of herceptin.
Epidermal growth factor receptor
The epidermal growth factor receptor (EGFR or HER1) is a type 1 tyrosine kinase receptor that normal breast tissue. Generally speaking, higher than expected levels of EGFR are accompanied by low levels of estrogen receptors and other poor prognostic features. EGFR tends to be associated with grade III breast tumors.
Basal breast tumor markers
Some breast tumors may express high levels of proteins that are not normally associated with epithelial cells (like duct-lining cells most commonly associated with breast cancer) but are rather derived from basal or myoepithelial cells.
There are a number of proteins associated with basal and myoepithelial gene expression, including:-
- cytokeratins 5 6, and 14
Most of these tumors also have a corresponding low expression of ER, PgR, and HER2, and have a higher risk of metastasis (especially to the lung).
Markers of breast cancer ‘proliferation’
An antigen Ki-67 is expressed in the nucleus of neoplastic cells in all phases of a cell cycle, and is therefore thought to be a useful marker for high levels of proliferation.
Notable changes in Ki-67 expression following a neoadjuvant treatment by endocrine therapy has been shown to be a useful predictor of long term outcome in some cases.
If one can inhibit new cell growth , Ki-67 levels will also decrease, and this tends to predict a good response to chemotherapy. Other proliferation markers in use in some breast cancer research centers include:-
However, in practical terms it is still the presence of estrogen and progesterone receptors which remain the most reliable and useful predictive marker for the staging and management of breast cancer.
Epidermal growth factor receptors, Ki-67, and Topoisomerase II alpha have high potential as prognostic markers of breast cancer, while other markers such as:-
- cyclin E
- cyclin D1
are still in an experimental phase, with limited clinical applicability.
Molecular and genetic aspects are important in Breast Cancer Histology
In the future, (and in some cases presently) micro array-based high-throughput technologies might be employed to look more closely at the molecular characteristics of breast cancers.
Certain genetic/molecular features have been associated with an increased proclivity to metastasize. Certainly, the more you know about the tumor, the more fine-tuned can be the treatment. In addition, it is possible that in the near future these genetic and molecular features of a breast tumor might be included in the determination of histological breast cancer grade.
For further reading, I suggest you go to this page with information on chances of having a breast cancer diagnosis, and visit this page for the number of breast cancer and DCIS cases diagnosed per year. Also, visit this page to know some information on breast cancer treatments overview, as well as this page for histology grade changes risk for ADH and DCIS.<
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