Benjamin Daniels1, Belinda E Kiely2, Sarah J Lord2,3, Nehmat Houssami4, Christine Y Lu5, Robyn L Ward6, Sallie-Anne Pearson7. 1. Medicines Policy Research Unit, Centre for Big Data Research in Health, UNSW, Sydney, Australia. b.daniels@unsw.edu.au. 2. NHMRC Clinical Trials Centre, University of Sydney, Sydney, Australia. 3. School of Medicine, University of Notre Dame Australia, Sydney, Australia. 4. Sydney School of Public Health, Faculty of Medicine and Health, University of Sydney, Sydney, Australia. 5. Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, USA. 6. University of Queensland, Brisbane, Australia. 7. Medicines Policy Research Unit, Centre for Big Data Research in Health, UNSW, Sydney, Australia.
Abstract
PURPOSE: Patients treated with trastuzumab for HER2-positive metastatic breast cancer (HER2+MBC) are living longer, but there is little information on their outcomes and treatment experience beyond the median survival from clinical trials and real-world observational studies. We aim to describe the real-world treatment patterns and overall survival (OS) for women surviving five or more years from initiation of trastuzumab for HER2+MBC. METHODS: This is a retrospective, whole-of-population cohort study of women initiating trastuzumab for HER2+MBC between 2001 and 2011, followed to 2016. We defined long-term survivors (LTS) as those patients surviving ≥ 5 years from trastuzumab initiation. We used dispensing claims to describe timing of cancer treatments used by LTS and to estimate time on and off HER2-targeted therapies, and OS from trastuzumab initiation for HER2+MBC. RESULTS: Of 4177 women initiating trastuzumab for HER2+MBC, 1082 (26%) survived ≥ 5 years. Median age for LTS was 54 years (IQR 46-63). At a median follow-up of 9.4 years, 36% of LTS died; their conditional probability of surviving an additional 5 years was 55%. Median time on trastuzumab and all HER2-targeted therapy was 58.9 months (27.6-88.1) and 69.1 months (35.6-124.5), respectively. 85% of LTS had a period off HER2 therapy, lasting a median of 30.4 months (8.2-NR). CONCLUSIONS: LTS generally receive HER2-targeted therapies for periods of time longer than in clinical trials, but most LTS also had breaks in treatment. More research is needed to understand the effects of long-term treatment and to identify patients who may be able to safely discontinue HER2-targeted therapy.
PURPOSE:Patients treated with trastuzumab for HER2-positive metastatic breast cancer (HER2+MBC) are living longer, but there is little information on their outcomes and treatment experience beyond the median survival from clinical trials and real-world observational studies. We aim to describe the real-world treatment patterns and overall survival (OS) for women surviving five or more years from initiation of trastuzumab for HER2+MBC. METHODS: This is a retrospective, whole-of-population cohort study of women initiating trastuzumab for HER2+MBC between 2001 and 2011, followed to 2016. We defined long-term survivors (LTS) as those patients surviving ≥ 5 years from trastuzumab initiation. We used dispensing claims to describe timing of cancer treatments used by LTS and to estimate time on and off HER2-targeted therapies, and OS from trastuzumab initiation for HER2+MBC. RESULTS: Of 4177 women initiating trastuzumab for HER2+MBC, 1082 (26%) survived ≥ 5 years. Median age for LTS was 54 years (IQR 46-63). At a median follow-up of 9.4 years, 36% of LTS died; their conditional probability of surviving an additional 5 years was 55%. Median time on trastuzumab and all HER2-targeted therapy was 58.9 months (27.6-88.1) and 69.1 months (35.6-124.5), respectively. 85% of LTS had a period off HER2 therapy, lasting a median of 30.4 months (8.2-NR). CONCLUSIONS: LTS generally receive HER2-targeted therapies for periods of time longer than in clinical trials, but most LTS also had breaks in treatment. More research is needed to understand the effects of long-term treatment and to identify patients who may be able to safely discontinue HER2-targeted therapy.