Breast cancer is a familiar type of cancer that begins in the breast tissue. It arises when cells in the breast begin to grow and divide uncontrollably, forming a lump or mass known as a tumor. Breast cancer can be classified into different types depending on the existence of certain proteins, such as estrogen, progesterone receptors, and the HER2 protein.

Human epidermal growth factor receptor 2 (HER2) gene is a protein on the cell’s surface. It belongs to the family of epidermal growth factor receptor (EGFR) proteins that regulate cell growth and division. In some cases, this gene can become amplified, leading to an overexpression of the HER2 protein. Hence too much HER2 protein can cause cells to grow and divide more quickly than normal, leading to cancer development. HER2-positive breast cancer is a subtype of breast cancer characterized by overexpression and tested positive for the HER2 gene, which promotes the growth of cancer cells.

Diagnosis of HER2-positive breast cancer

Diagnosing HER2-positive breast cancer is done through a combination of tests, including a breast biopsy and HER2 testing.

• A breast biopsy involves extracting a small sample of breast tissue which is then analyzed under a microscope to detect any potential cancer cells. The procedure can be performed either through a needle biopsy or a surgical biopsy.
  
  
• HER2 testing: After identifying cancer in the biopsy sample, the subsequent step is to assess whether the cancer cells are HER2-positive by conducting a laboratory test. The two widely used tests for HER2 testing are:
  
  
• Immunohistochemistry (IHC) is a laboratory test commonly used to determine if breast cancer is HER2-positive. The test involves staining a cancer tissue sample with antibodies that bind specifically to the HER2 protein. It is observed under a microscope. The IHC test is a valuable tool in determining the HER2 status of breast cancer, as it is cost-effective and can be performed on standard laboratory equipment. It is also highly accurate when performed by experienced laboratory personnel.
  
  
• Fluorescence in situ hybridization (FISH) test involves using fluorescently labeled DNA probes that bind specifically to the HER2 gene on the cancer cells. The probes are applied to the cancer tissue samples and allowed to hybridize, or bind, to the HER2 gene. Any excess probes that do not bind to the HER2 gene are washed away and observed under a fluorescent microscope. If the test results show that the cancer cells are HER2-positive, the cancer is classified as HER2-positive breast cancer.
  
  Prevention of HER2-positive breast cancer
  
  Several lifestyle changes and strategies may help reduce the risk of developing or detecting the disease early when it is most treatable.
  
  
• Regular breast exams: Women should perform monthly breast self-exams and schedule regular clinical breast exams to detect any changes or abnormalities in the breasts.
  
• Mammograms: Mammography is a low-dose x-ray imaging technique that can detect abnormalities or changes in breast tissue indicative of cancer. Mammography can detect breast cancer early when it is most treatable. Women should have regular mammograms to detect any breast changes or abnormalities indicative of breast cancer.
  
• Healthy lifestyle: Women can reduce their risk of developing breast cancer by maintaining a healthy lifestyle, including regular exercise, a healthy diet, a healthy weight, and limiting alcohol intake.
  
• Hormone therapy: Hormone therapy, such as birth control pills or hormone replacement therapy, may increase the risk of developing breast cancer. Hormone therapy drugs, like tamoxifen or aromatase inhibitors, may block the effects of these hormones and reduce the risk of recurrence.
  
• Genetic testing: Genetic testing typically involves a blood or saliva sample that is analyzed in a laboratory to detect the presence of specific genetic mutations. Women with a family history of breast cancer or other risk factors undergo this test to determine if they have an inherited DNA alteration (mutation).
  
  Screening for HER2-positive breast cancer typically involves mammography or other imaging tests, such as breast ultrasound or MRI, to detect abnormalities or changes in breast tissue. The treatment of HER2-positive breast cancer typically involves a combination of surgery, radiation therapy, chemotherapy, and targeted therapy.
  
  Perjeta 420 injection (pertuzumab) is a targeted therapy used to treat HER2-positive breast cancer. It works by binding to the HER2 receptor on cancer cells and blocking its ability to signal the growth and division of the cancer cells. This can slow or stop the growth of cancer and potentially shrink tumors. The most common side effects of Perjeta 420 injection is hair loss, sore mouth, constipation, poor appetite, changes in taste, sleeping troubles, nose bleeds, heartburn, nail problems, producing more tears, and feeling dizzy, dry and itchy skin.