Real-world impact of TAILORx on chemotherapy use and SOFT/TEXT on ovarian function suppression uptake in a population based-cohort of women 40 years and under with HR-positive, HER2-negative, axillary lymph node negative breast cancer.

person Malek B. Hannouf Schulich School of Medicine and Dentistry, Department of Internal Medicine, Western University, London, ON, Canada info_outline Malek B. Hannouf, Kim Koczka, Muriel Brackstone, Sasha M. Lupichuk

Authors person Malek B. Hannouf Schulich School of Medicine and Dentistry, Department of Internal Medicine, Western University, London, ON, Canada info_outline Malek B. Hannouf, Kim Koczka, Muriel Brackstone, Sasha M. Lupichuk Organizations Schulich School of Medicine and Dentistry, Department of Internal Medicine, Western University, London, ON, Canada, BC Cancer Agency, Surrey, BC, Canada, London Health Sciences Center, London, ON, Canada, Tom Baker Cancer Centre, Calgary, AB, Canada Abstract Disclosures Research Funding No funding received None. Background: Gene expression profiling (GEP) testing is prognostic for distant recurrence risk in women with hormone receptor positive (HR+), human epidermal growth factor receptor-2 negative (HER2-), axillary lymph node negative (LN-) breast cancer (BC). The TAILORx trial generated prospective evidence demonstrating the 21-gene recurrence score (RS) is also predictive of chemotherapy (CT) benefit. The literature suggests that GEP testing reduces adjuvant CT prescription and is cost-effective. In the same era, the SOFT/TEXT trials demonstrated disease-free survival benefit for the addition of ovarian function suppression (OFS) to endocrine therapy in premenopausal women. Real-world uptake and impact of these advances in the management of HR+, HER2-, LN- BC in young women may be limited due to complex reasons. This retrospective study evaluated GEP and CT use post TAILORx and OFS use post SOFT/TEXT in women 40 years old or younger diagnosed with HR+, HER2-, LN BC from 2011 to 2020 in Alberta, Canada. Methods: Clinical variables were retrieved from the Alberta Health Services Cancer Care Breast Data Mart and through review of the electronic medical record. GEP testing and CT use were compared between 3 cohorts of women defined by diagnosis: pre RS funding/pre TAILORx (before April 2014), post RS funding/pre TAILORx (April 2014-May 2018), post TAILORx (June 2018 and beyond). OFS use was compared between 2 cohorts of women defined by diagnosis pre- and post SOFT/TEXT (May 2015). In subgroup analyses, we compared CT use by GEP status and RS category and OFS use by CT status. Results: Among the 291 women identified, GEP testing increased by 37% post GEP funding (pre 2% vs. post 39%; P = < .0001) and by additional 15% post TAILORx (pre 39% vs. post 54%; P < .0001) whereas overall CT use declined by 15% post GEP funding (pre 85% vs. post 70%; P = .01) and by additional 16% post TAILORx (pre 70% vs. post 54%; P = .01). Although not significant, OFS use increased by 8% post SOFT/TEXT (pre 13% vs. post 21%; P = .08). In subgroup analyses, post TAILORx was associated with a significant reduction in CT use of 19.5% in non-GEP tested women (pre 85% vs. post 65% P = .01) and non-significant increase in CT use of 6% in RS tested women (pre 40% vs. post 46%; P = .61) mainly driven by high mid range RS 21-25 and lower high range RS 26-30. There was no significant change in OFS use in non-CT treated women post SOFT/TEXT (Pre 5.3% vs. Post 8%, P = .68) whereas OFS use increased by 15% in women treated with CT post SOFT/TEXT (pre 15% vs. post 30%; P = .01). Conclusions: Public GEP funding and TAILORx led to widespread adoption of GEP and real-world decline in CT use in women 40 years of age or younger diagnosed with HR+, HER2-, LN- BC in Alberta. SOFT/TEXT led to real-world incline in OFS use in those treated with CT but adoption remained suboptimal.