HER2 Positive Breast Cancer is a variant of breast cancer. The patient in this case shows positive test for the presence of human epidermal growth factor- receptor 2 abbreviated as HER2. Human epidermal growth factor induces a brisk growth in cancer cells which might spread to other organs of the body or become metastatic.

One must know about receptors and growth factors for having detailed understanding of HER2 positive breast cancer:

Receptors: Receptors are specialized proteins present inside or on the surface of a cell. Other chemicals or proteins in the body could attach to these receptors to convey a change in the cellular metabolism like reproduction and repairing.

Growth Factors: These are the chemicals, which bind to the receptor and induce growth in the cell.

HER2 is a distinctive receptor present on the outer wall of cancer cells. It is made by specific genes called HER2 gene/neu gene. HER2 is a receptor for human epidermal growth factor a chemical that occurs in body naturally. When the human epidermal growth factor attaches to HER2, it stimulates the cancer cells to grow and divide rapidly.

In 1 out of every 5 breast cancer patients, the HER2 gene gets altered / mutated to produce more than one HER2 receptor in a cell thus inducing an aggressive growth of the cancerous mass. Some form of breast cancer has more than normal HER2 receptors and hence these patients are diagnosed for positive HER2 breast cancer.

Testing and Diagnosis of HER2 Positive Breast Cancer

The two key methods used to test HER2 Positive Breast Cancer are:

1. Immunohistochemistry: Immunohistochemistry (ICH) tests the extent of HER2 present in a tumor sample. According to this test HER2 level is graded from 0 to 3+
   • 0-1+ indicates normal amount of HER2 and hence the patient is tested negative
   • 2+ means moderate amount of HER2 Protein
   • 3+ signals higher number of HER2 than normal and thus a patient is tested positive
2. Fluorescence in-situ hybridization (FISH): Dissimilar to ICH, FISH measures the amount of HER2 gene/neu Gene present in each cell. There is no range or scale for FISH Testing, it is either FISH Negative (Normal level of genes present) or FISH Positive (Gene amount is more than normal)

Treatment for HER2 Positive Breast Cancer

HER2 breast cancer is more aggressive than any other type of breast cancer. As stated by National Cancer Institute that 95% of breast cancer patients have positive HER2 number. This form of breast cancer is submissive to any hormonal treatment for breast cancer. Instead, if it is targeted specifically the results are more productive. These include:

1. Trastuzumab (Herceptin) Based Treatment: Herceptin targets the cancer cells and kills them thus shrinking the cancerous mass. Herceptin could be given with a chemotherapy drug or in combination with a hormone treatment. Some common side effects of Herceptin are congestive heart failure and allergy
2. Lapatinib (Tykerb) Based Treatment: Lapatinib is similar to Herceptin but is administered to patients who show no improvement with Herceptin. It could be introduced in combination with chemotherapy drug capecitabine (Xeloda) and the aromatase inhibitor letrozole (Femara).
3. Adriamycin Based Treatment: Chemotherapy drugs like Adriamycin or Doxorubicin could be used to treat HER2 Breast Cancer. However, these drugs do not target HER2 Proteins specifically. Cancer treatment using adriamycindoxorubicin chemotherapy is an effective treatment option as it is used for the treatment of multiple cancers.

There are a lot of methods available for treating HER2 positive breast cancer. But, as it is the most critical and dangerous type of cancer, it is important that one opts for an effective and best treatment.