Specific Aim 2: We hypothesize that histopathological tumor response will be demonstrated in 30-40 percent of patients with preinvasive (DCIS) and early invasive (less than 2 cm) breast cancer treated with anastrozole. The percent ability to reverse early breast cancer lesions in patients treated with anastrozole will be qualified as a secondary surrogate endpoint to breast cancer risk reduction. Consistent with this, it has been demonstrated that 30-40 percent of patients with advanced breast cancer show an infiltration of foamy macrophages and fibrosis on lumpectomy/mastectomy samples when chemotherapy is administered for few months prior to definitive surgery. Further, there is a trend for a more profound change in those achieving a complete clinical response. Importantly, a complete pathological response in these advanced breast cancer has been shown to correlate with improved disease free survival and overall survival in breast cancer patients. A corollary is that if reversibility of early carcinogenic lesions is reliably demonstrated in our present proposal, it would translate into chemoprevention of breast cancer.