Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2023

National retrospective cohort study of safety and effectiveness of erlotinib and gefitinib in New Zealand for treating EGFR mutated lung cancer: Study protocol and results of the validation sub-study (#302)

Phyu Sin Aye 1 , Joanne Barnes 1 , George Laking 1 , Laird Cameron 2 , Malcolm Anderson 3 , Brendan Luey 4 , Stephen Delany 5 , Dean Harris 6 , Blair McLaren 7 , Ross Lawrenson 8 , Michael Arendse 9 , Sandar Tin Tin 1 , Mark Elwood 1 , Philip Hope 10 , Mark James McKeage 1
  1. University of Auckland, Auckland, New Zealand
  2. Te Whatu Ora Health New Zealand, Auckland, New Zealand
  3. Palmerston North Hospital, Palmerston North, New Zealand
  4. Wellington Hospital, Wellington, New Zealand
  5. Nelson Marlborough District Health Board, Nelson, New Zealand
  6. Te Whatu Ora Waitaha Canterbury, Christchurch, New Zealand
  7. Southern District Health Board, Dunedin, New Zealand
  8. University of Waikato, Hamilton, New Zealand
  9. Waikato Hospital, Hamilton, New Zealand
  10. Lung Foundation New Zealand, Auckland, New Zealand

Background: The Epidermal Growth Factor Receptor (EGFR) inhibitors, erlotinib and gefitinib, were introduced into routine use in New Zealand (NZ) for treating advanced lung cancer in 2010, but their impact in that setting is unknown. This study aims to understand the effectiveness and safety of these new personalised lung cancer treatments. The study protocol and results of the validation sub-study are presented.

Methods: This retrospective cohort study will include all NZ patients with advanced EGFR mutation-positive lung cancer, who were first dispensed erlotinib or gefitinib up to 30 September 2020 and followed until death or ³1 year. Routinely collected health administrative and clinical data will be collated from national electronic cancer registration, hospital discharge, mortality registration and pharmaceutical dispensing databases, by deterministic data linkage using National Health Index numbers. The primary effectiveness and safety outcomes will be time-to-treatment discontinuation and serious adverse events, respectively. The primary variable will be concurrent use of high-risk medicines with erlotinib or gefitinib. A validation sub-study was undertaken of national electronic health databases as the data source, and methods for determining patient eligibility and identifying study outcomes and variables.

Results: National electronic health databases and clinical records agreed in determining patient eligibility and for identifying serious adverse events, high-risk concomitant medicines use and other categorical data, with overall agreement and Kappa statistics of >90% and >0.8, respectively. Dates for estimating time-to-treatment discontinuation and other numerical data showed small differences, mostly with nonsignificant p-values and confidence intervals overlapping with zero difference.

Conclusions: A protocol is presented for a national whole-of-patient-population retrospective cohort study to describe the safety and effectiveness of erlotinib and gefitinib during their first decade of routine use in NZ for treating EGFR mutation-positive lung cancer. This validation sub-study demonstrated the validity of using national electronic health databases and methodologies to determine patient eligibility and identify study outcomes and variables. Study registration: ACTRN12615000998549.