HER-2/neu

My mother has right whole breast removed and her 9 lymph nodes are negative. That is good news, right? Her receptors (estrogen and progesterone) are negative. What does this mean? The ratio of HER-2 to CEP17 is greater than 4.0. I understand that is higher risk for cancer to come back and a shorter disease-free survival. Is that right interpretation? Would you please explain more about HER-2/neu and receptors? Is there any way to prevent that? What are side effects? What will she goes through with drug trastuzumab (Herceptin)? What does that drug will do?
Thank you

[CCF-RN,MSN-rf]

Dear bo7911:  Tumors that are HER2 positive have tended to be more aggressive, shorter disease free survival, higher recurrence.  Having said that, it means that herceptin may be effective in treating this.  The following is how herceptin is designed to work:

Monoclonal antibodies are a relatively new type of