Long-Term Results Show Comparable Efficacy for Anastrozole and Tamoxifen

Halle Moore, MD, an oncologist in the department of hematology and medical oncology at the Cleveland Clinic, discusses the results of the IBIS-II DCIS trial (NCT00072462) of anastrozole versus tamoxifen after 12 years of follow-up for postmenopausal patients with locally excised ductal carcinoma in situ (DCIS).

The original presentation of this trial did not show a difference between these 2 agents but demonstrated the noninferiority of anastrozole when compared with tamoxifen, according to Moore. There were no significant variances in the risk of recurrence of these patients in the updated analysis, with about a 1% difference. For invasive recurrence or more rarely death from breast cancer in these patients with noninvasive breast cancer, there were no changes in the outcomes for these 2 drugs. The main difference was for the toxicity profiles.

Moore says that this trial shows there are options for patients with DCIS. Patients with severe osteoporosis with concerns of muscular-skeletal symptoms may be prescribed tamoxifen as a risk-reducing agent. On the other hand, patients at risk for blood clots or uterine cancer may receive an aromatase inhibitor. Both are reasonable options to consider in this setting, she thinks.