This test is recommended for a person who is diagnosed with breast cancer. This test helps determine if a tumour is positive for HER2/neu. This test is conducted to see if the patient may benefit from the treatment with trastuzumab, which is a drug that was created to fight HER2. This test also acts as a prognostic marker to see how aggressive the tumour is. This way, the doctor is able to come up with a suitable treatment plan for the patient and he will be able to understand a tumour better. This test is prescribed along with estrogen and progesterone hormone receptor status tests (ER and PR).