Arimidex vs chemo

My dear friend (55) has been diagnosed with infiltrating ductal carcinoma which spread to the lymph nodes. After all of the scans and tests they put her on Arimidex  instead of  chemo. My question is why? Is the arimidex better then chemo? What is the difference between the too?

[Cleveland Clinic]

Dear debbie2213:  Without knowing the particulars of your friend’s situation, it is impossible to speculate on what the choices may be and how decisions were made as to the treatment.  Arimidex is a medication that suppresses estrogen in tumors that are estrogen positive.  It would only have a role in tumors that are hormone receptor positive.  Chemotherapy is directed at any and all cancer cells.  Sometimes both are appropriate to a situation and sometimes one or the other would be the choice.