ASCO recently endorsed the Cancer Care Ontario (CCO) guideline on adjuvant ovarian ablation (OA) to treat premenopausal women with early stage, invasive breast cancer. The CCO guideline, published in 2010, recommends against incorporating OA into treatment regimens or as mono-therapy. To read the ASCO endorsement in JCO, please visit www.asco.org/endorsements/OA; for patient information, visit Cancer.Net.