Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2022

Beyond the median: estimating survival times for patients starting endocrine therapy for estrogen receptor positive metastatic breast cancer (#223)

Andrew O Parsonson 1 2 , Sunit Sarkar 3 , Lauren Brown 4 , Belinda E Kiely 1 5 , Anuradha Vasista 5 6
  1. Macarthur Cancer Therapy Centre, Campbelltown, NSW, Australia
  2. Macquarie University, North Ryde, NSW, Australia
  3. Royal Hobart Hospital, Hobart, Tasmania, Australia
  4. Crown Princess Mary Cancer Centre, Westmead, NSW , Australia
  5. University of Sydney, Camperdown, NSW, Australia
  6. Nepean Cancer Care Centre, Penrith, NSW , Australia

Background: Using estimated scenarios for survival to explain life expectancy to patients conveys more meaning and hope than single point estimates of the median overall survival1.

Aim: To assess whether using simple multiples of median survival could accurately assess scenarios for survival for patients with estrogen receptor (ER) positive, metastatic breast cancer (MBC) starting endocrine therapy (ET)  

Methods: We systematically searched for randomised trials of ET for ER positive MBC. We then recorded the following percentiles (representative scenarios) from each overall survival (OS) curve: 90th (worst-case), 75th (lower-typical), 50th (median) 25th (upper-typical), and 10th (best-case). The accuracy of estimating these percentiles for each OS curve was assessed by multiplying its median by four simple multiples: 0.25 (to estimate the 90th percentile), 0.5 (75th), 2 (25th) and 3 (10th). Estimates were deemed accurate if within 0.75 -1.33 times the actual value.

Results: We identified 24 trials with 10,068 patients. The median OS (interquartile range [IQR]) was: 61.3 months (53.4-64.8) for first-line ET with cyclin-dependant kinase 4/6 inhibitors (CDK4/6i) (4 treatment groups); 42.6 months (40.9-50.4) for first-line ET alone (22 treatment groups) and 29.2 months (24.8-33.4) for subsequent line ET (21 treatment groups). The median OS (IQR) for each scenario for first-line ET with CDK4/6i was: worst-case 17.4 months (13.8-20.7); lower-typical 32.5 months (29.3-34.9); upper-typical and best-case percentiles were not available. Simple multiples of the median OS accurately estimated the 90th percentile in 79%; 75th percentile in 93%; and 25th percentile in 76% of curves. The 10th percentile was only available for four OS curves and could not be accurately assessed.

Conclusion: Using simple multiples of the median OS to estimate and explain survival times to patients with MBC starting ET, is accurate and meaningful. Longer follow-up of trials is required to help clinicians estimate the best-case scenario for these patients.

  1. Kiely BE, McCaughan G, Christodoulou S, et al. Using scenarios to explain life expectancy in advanced cancer: attitudes of people with a cancer experience. Support Care Cancer 2013; 21: 369-376. 2012/06/22. DOI: 10.1007/s00520-012-1526-4.