What is HER2 test and how it works
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In Singapore, breast cancer accounts for almost 30 per cent of cancers in women.
PHOTO: ISTOCKPHOTO
The test which produced inaccurate results for 180 women is used to determine how aggressive a patient's breast cancer is likely to be, so doctors can offer the right treatment.
It checks for human epidermal growth factor receptor 2 (HER2) proteins, which normally regulate the healthy growth of breast tissue.
The test works by introducing antibodies tagged with a coloured dye to a sample of breast tissue. These attach themselves to HER2 proteins, which show up as a stain when a doctor observes the sample under a microscope.
The intensity of the stain determines whether the result is positive or negative.
The gene that produces the protein can cause uncontrolled tissue growth if it malfunctions.
If a breast cancer patient is HER2-positive, it means she is likely to have a tumour that is more aggressive than those in HER2-negative patients.
She will probably respond poorly to certain treatments such as standard chemotherapy or hormone therapy. The patient may be considered for HER2-specific treatments such as the drug Trastuzumab, which works by attaching itself to HER2 receptors on breast tissue cells to block them from receiving growth signals.
The drug can cause side effects such as diarrhoea, chills and fever. It can also cause heart problems in about 3 per cent to 4 per cent of patients.
