Is arimidex (anastrozole) when given as prevention of recurrence of breast cancer only used with estrogen receptive cancer?

Yes* Arimidex (anastrozole) belongs to a category of drugs called aromatase inhibitors. These are effective chemotherapeutic agents for people with either estrogen-sensitive or *progesterone-sensitive breast cancers. This is only effective after menopause; premenopausal women may use tamoxifen for a similar response rate.
Yes. This question is nicely answered by a free article from jco: http://jco.Ascopubs.Org/content/23/8/1636.Full neither Arimidex (anastrozole) nor tamoxifen seem to have much effect on receptor-negative breast cancer.