Breast cancers with HER gene amplification or HER protein overexpression are called HER positive in the pathology report. HER positive breast cancers tend to grow faster and are more likely to spread and come back compared to HER negative breast cancers. But there are medicines specifically .HER is a protein that causes breast cancer cells to grow, and can cause aggressive breast cancer. Read about survival rates, treatments, and more..HER neu often just shortened to HER is a growth promoting protein on the outside of all breast cells. Breast cancer cells with higher than normal levels of HER are called HER positive. These cancers tend to grow and spread faster than other breast cancers. Women newly diagnosed with invasive breast cancers .Normally, human epidermal growth factor receptor HER helps control how a healthy breast cell divides, grows, and repairs itself. However, when the HER gene is abnormal, it causes the cells to divide and grow at an uncontrolled rate. HER positive breast cancer is a more aggressive type of breast .