Highlights from

BCC 2019

St. Gallen International Breast Cancer Conference

Vienna 20-23 March 2019

St. Gallen Consensus - Endocrine therapy in premenopausal patients

The first question the panel had to answer on this topic was the ideal cut-off – in terms of percentage of ER-positive tumour cells – to prescribe endocrine therapy. There was no clear consensus on this topic: 30% of the panellists voted for >1%, 4% voted for >5%, 39% voted for >10%, while 25% took the view that there is no clear answer. Recently, updates were presented of the SOFT and TEXT trial [1] showing that among premenopausal women with breast cancer, the addition of ovarian suppression to tamoxifen resulted in significantly higher 8-year rates of both disease-free and overall survival than tamoxifen alone. The use of exemestane plus ovarian suppression resulted in even higher rates of freedom from recurrence. Based on these results, a majority of the panellists (68%) took the view that premenopausal patients with an ER-positive tumour who are getting adjuvant chemotherapy are candidate for ovarian function suppressive (OFS) therapy. Also in line with the SOFT and TEXT trials, 85% of the panellists agreed that an age <35 years should lower the threshold to prescribe OFS therapy. There was no consensus on the question whether premenopausal ER-positive patients with a moderate risk and no adjuvant chemotherapy are candidate for OFS: 46% voted “yes”, 42% voted “no.” A small majority of the panellists (60%) was of the opinion that an adverse result of a gene expression test should lower the threshold for OFS therapy in premenopausal ER-positive patients. Half of the panellists (52%) was of the opinion that Her2-positive status should not lower the threshold for OFS therapy. Asked for their opinion on the duration of OFS, a small majority of the panellists (55%) favoured 5 years of OFS, which was the duration of OFS in the SOFT and TEXT trial (24% voted for 2-3 years of OFS). A majority of the panellists endorsed OFS during chemotherapy for women who want a future pregnancy. This was the case for patients with HR-negative breast cancer (92% voted “yes”), and for patients with HR-positive breast cancer (80% voted “yes”). With regard to preferred endocrine therapy for patients who remain premenopausal after 5 years of tamoxifen therapy, a small majority of the panellists recommended to stop further treatment with tamoxifen, while 37% of the panellists recommended to continue to 10 years of treatment with tamoxifen. However, in case the patient – who remained premenopausal after 5 years of tamoxifen – was at high risk at presentation (e.g. stage 2, node positivity), 80% of the panellists would recommend continuing tamoxifen treatment to 10 years.

  1. Francis PA, et al. N Engl J Med 2018; 379: 122-137.

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The content and interpretation of these conference highlights are the views and comments of the speakers/authors.