Abstract Abstract #1148 Background: Women aged under 55 receiving breast cancer treatment frequently experience temporary or permanent menopause as a result. Although defining menopause status in these patients is problematic it fundamentally influences subsequent medical management. No definitive data or consensus exists to guide what surveillance is required in these women, particularly with respect to treatment with aromatase inhibitors (AIs) and/or ovarian suppression and for contraceptive advice.The ENHANCE Group, first convened in Australia in 2006, consists of 19 members, comprising Medical Oncologists, Breast Surgeons, Endocrinologists, Gynaecologists and a Consumer Representative. The aim of the Group is to develop practical advice on the management of QoL and adverse event issues associated with hormonal therapy of breast cancer in areas where high-level evidence is insufficient to inform practice. The Group produces recommendations for healthcare professionals and information leaflets for patients. All recommendations are supported with the maximum evidence available together with broad expert opinion.
 Methods:A review of the literature identified information regarding the definition of menopause, tests of menopause status and likelihood of menopause following different adjuvant chemotherapy regimens. Data on the likelihood of return of ovarian function was also identified. In addition, the use and benefit of ovarian function suppression and AIs for treatment of different subpopulations of breast cancer patients was reviewed. Using this review and expert opinion provided by members of the Group, an algorithm for determination of menopausal category was developed. Management recommendations, according to menopausal category were then determined.
 Results:Five distinct menopause categories were identified: Premenopausal, Postmenopausal, Very Low, Low, and Moderate potential for ovarian function recovery. Menopausal status prior to adjuvant chemotherapy, type of adjuvant treatment, age, duration of amenorrhoea, oestradiol and FSH levels and use of tamoxifen determined placement into the categories. The algorithm includes suggested monitoring practice, both clinical and biochemical, for each of the menopause categories and guidance for patients who have had a hysterectomy. The recommendations indicate: (i)contraceptive advice according to age and menopause category; (ii)appropriate use of AIs with suggested monitoring practices; (iii)monitoring suggestions for patients where ovarian function suppression may be appropriate (iv)advice to be provided to patients to assist in monitoring menopausal status. A separate information sheet was developed to inform patients about menopause monitoring.
 Conclusions:Ovarian function can return after a considerable period of amenorrhoea in patients undergoing systemic treatment for breast cancer. Return of ovarian function influences endocrine treatment of breast cancer, but it is often difficult to monitor accurately, and an appropriate schedule has not been investigated. Our work provides evidence-based recommendations (including expert opinion) for best practice in this area. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1148.