IHC – IMMUNOHISTOCHEMISTRY

IHC – IMMUNOHISTOCHEMISTRY

IHC – is a process which involves staining of cancer tissue. This cancer tissue removed during biopsy may be fresh or frozen. This technique essentially involves the evaluation of cancer cells to determine their HER2 receptor and/or hormone receptor status. This information is a key player in prescribing the treatment and defining the prognosis of the condition.

IHC for HER 2 Testing

This test mainly assesses the HER2 status of the cancer cells, by testing the protein presence of the cancer cell surface. These receptors are alert to the growth signals of the HER2 receptor proteins and receive signals for growth stimulation. Thus dividing and multiplying rapidly giving an aggressive growth status to the tumor. A score of 0 – 3+ in IHC is used to define a positive or a negative status of the cancerous growth. A score of 0 to 1+ is HER2 negative and a score of 2+ is a borderline score. A cancerous growth is given a positive status if the score is more than 3+.

It has been observed that in the same cancer growth different parts of the growth may test positive and some may test negative for HER2 receptors. These results may be diagnosed as HER 2 positive for an HER2 negative score in some cases. A wrong diagnosis may lead to a faulted treatment which may not benefit the women diagnosed. This is due to the fact that different lbs and different pathologists have different scoring criteria. Also if one part tests as negative and one part of breast cancer is HER 2 positive the doctor may not recommend medicines that would work against HER2 positive growth.

To remove any doubts for cases scoring a borderline measure in the IHC test for HER2 receptors, it is best advised that the patient is prescribed FISH test. This test is a conclusive test for HER2 testing and uses a different technology for measuring of HER2 status.

IHC test gives best results on cancerous tissue which is fresh or frozen, not treated or fixed. IHC for hormone receptor testing.

IHC test also utilizes the technique to evaluate the presence of hormone receptors on the surface of breast cancer cells. The presence of hormone receptors on the surface of the breast cancer cells is evident of the fact that these cancer cells are growing and multiplying by the hormones estrogen and/or progesterone.

  • One method is of “Allred score” which measure the percentage of cells which have tested positive for hormone receptors. Also as staining is involved in IHC, it defines the staining in “ intensity”. Both these parameters are combined to rate the tissue between a score of 0 to 8. A higher score means more number of hormone receptor cells. This test is named after the doctor who developed the test.
  • A numbering score of 0 to 3. 0 denotes no hormone receptor cells, 1 denotes a minimal amount, 2 denote medium amount of receptor cells and 3 means a large number.
  • A percentage scoring – 0 % means no receptor cells and 100% means all surface cells of the tissue have hormone receptor cells.
  • “positive” or “negative”

This test would only benefit if it is performed for both estrogen receptors and progesterone receptors. Different labs and doctors have different scoring and rating system . as such a negative score may means positive for another lab. Thus unless a score is 0, it is advisable that the patient is put on hormonal therapy for complete elimination of receptor cells to contain cancer growth and multiplication.

Only a score of 0 should be used to rule out the option of hormonal therapy as atreatment choice. Aromatse inhibitors, estrogen receptor down regulators and selective estrogen receptor modulators can be used to treat the condition.

Apart from a negative or a positive scoring of the tissue sample, sometimes an “unknown” status of the report is also given. This would mean that probably the sample was too small to be able to obtain accurate and reliable results. Or may be the test was not performed on the sample tissue. Lastly, it might also mean the presence of few estrogen and progesterone receptors. It is best that a negative status is reconfirmed with the doctor, and if required the test repeated. Alternatively, a different test may also be done on the tissue sample.

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