Your doctor could request extra blood tests if you are told you have breast cancer to help determine your prognosis. The HER2/neu test and the hormone receptor test are the two most popular laboratory procedures. Depending on the results of these tests, you may be able to determine which cancer treatment options are best for you.
Testing The Tumor Cells For Hormone Receptors
A hormone receptor is a specific protein found within or on the surface of a cell. The feminine hormones progesterone and oestrogen, which circulate in the blood, attach to the receptor. After binding, the hormone instructs the cell to begin dividing and expanding.
Hormone receptors are present in breast cancer tumours, frequently in high concentrations. Estrogen and/or progesterone can promote the development of malignancy when hormone receptors are present. Contrary to hormone replacement therapy, such hormone-dependent tumours frequently react effectively to hormone therapy (HRT). The malignancy is referred to as “hormone-receptor-negative” if neither progesterone receptors (PR) nor oestrogen receptors (ER) are present.
In this case, hormone therapy is likely to be ineffective. For the benefit of your medical team and your treatment strategy, it can be helpful to know whether the cancer cells have hormone receptors.
Who Needs Testing for Hormone Receptors?
All forms of breast cancer, including DCIS, should generally be subjected to hormone receptor testing. You might be advised to stop taking any prescribed hormones for a while before the breast tissue sample is taken if your doctor requests this test. The sample used for the test is typically taken from a biopsy, although it can also be tissue taken during a lumpectomy or mastectomy. But getting these pathology results on biopsy tissue is routine therapy.
How is the test conducted?
The testing lab normally performs a specialized staining procedure to determine whether hormone receptors are present in the breast tissue sample. An “immunohistochemical staining assay” or “ImmunoHistoChemistry (IHC)” is the formal name for this process. Your doctor will receive a pathology report with the results.
When a tumour is classified as “estrogen-receptor-positive” (ER+), its cells have oestrogen receptors. So, oestrogen likely sends signals to the cancer cells to encourage their proliferation. Hormone receptors are present in about two of every three breast cancer cases.
Progesterone receptor-positive (PR+) cancers have progesterone receptors on their cells. This hormone might then aid the growth of the malignancy.\
Being oestrogen and/or progesterone receptor-positive (hormone positive) in the cancer cells is a positive prognostic factor that typically results in a better prognosis.
What do the hormone test findings mean?
The prognosis for survival and full recovery is typically better than average for breast cancer patients who test positive for both oestrogen and progesterone receptors as opposed to those who do not. Also, they respond to hormone therapy better with more receptors and stronger their reaction. Individuals with only one receptor type may still benefit from this medication, although probably not to the same extent.
As was previously stated, hormone treatment is unlikely to be effective in treating cancer that is both ER- and PR-negative. The following are typical hormone treatment response rates:
- ER and PR favourable ER is 75–80% positive while PR is negative.
- PR is positive, and ER is 40–50% negative
- 25–30% of ER and PR tests are negative: 10% maximum
HER2/neu Test
The HER2/neu test, like the hormone receptor test, looks for a certain sort of protein present in particular types of cancer cells and the gene that makes it. The gene that produces HER2 proteins is officially known as the human epidermal growth factor receptor 2. On breast cells, these proteins act as receptors.
In a way, the amount and combination of proteins that a cell requires to stay healthy and perform as intended are calculated in the genes. Specific genes and the proteins they produce can influence breast cancer’s progression and response to various treatments.
What does breast cancer have to do with HER2 receptors, and how does it work?
The proteins that control a breast cell’s ability to multiply, develop, and repair itself are known as healthy HER2 receptors. Yet, the HER2 gene is dysfunctional in roughly 25% of all breast cancer patients. It engages in “HER2 gene amplification,” which is the process of making too many copies of itself. The cells are then instructed to produce excessive HER2 receptors, a condition known as “HER2 protein overexpression.” The end outcome is that breast cells multiply and expand out of control.
The HER2/neu test can determine whether the sample is normal, contains excessive HER2/neu protein, or how many copies of its gene are present. Your doctor could advise this test if you have had recurrent breast cancer or have been diagnosed with invasive breast cancer. It will assist your oncology team in determining your prognosis, the features of the tumour, including its likely level of aggressiveness, and the best course of therapy.
This test is often requested in addition to the hormone receptor test. Usually, a biopsy sample of breast cancer tissue or the tumour removed after a mastectomy is used. The pathology results of this test can take up to a week to get back, but it normally just takes a day or two to determine whether the cells are cancerous.
What will I learn from the HER2/neu results?
There are four HER2 tests, and the findings may be seen on your pathology report, which could take a few weeks to arrive.
IHC, which stands for “ImmunoHistoChemistry,” is the initial test. It examines whether the malignant cells have an overabundance of the HER2 protein. A score of 0 or 1+ shows no excess, 2+ is borderline, and 3+ indicates that the cells have overexpressed the HER2 protein.
The three left tests check to see if there are too many copies of the HER2 gene in the cells.
These tests consist of the following:
- “Fluorescence In Situ Hybridization” testing
- Subtraction Probe Technology Chromogenic In Situ Hybridization, or SPoT-Light HER2 CISH
- The Inform Dual In Situ Hybridization (Inform HER2 Dual ISH) test
For these three tests, there are only two possible outcomes: affirmative, which denotes HER2 gene amplification, and negative, which denotes an appropriate level of HER2 gene expression.
Breast tumours with HER2 protein overexpression and HER2 gene amplification are referred to as HER2-positive in the pathology report. Compared to HER2-negative breast cancer, this type of cancer frequently grows more quickly, spreads to other locations more easily, and is more likely to recur.
Testing for HER2/neu in blood
A blood sample is occasionally taken from the patient’s arm to gather comparable information, especially when there is not enough tumour tissue to do the test. This blood test, known as a “serum HER2/neu test,” may be used as part of the first evaluation following the cancer diagnosis or to assess the efficacy of treatment. The likelihood that the treatment is effective increases if the blood level of HER2/neu initially rises to more than 15ng/mL before falling. But, if the serum level continues to be elevated, the medication is ineffective. An indicator that cancer might be returning is when the serum level drops but then rises again when tested later.
When all three tests come back negative for receptors for hormones (progesterone and oestrogen) and negative for HER2, triple-negative breast cancer may be the diagnosis.
