Abstract: | AbstractBackground:Surgical resection of gastrointestinal stromal tumour (GIST) is rarely curative in patients at high risk of tumour recurrence and therefore 1 year of post-surgery adjuvant imatinib therapy has been recommended in this sub-group. Recently, adjuvant imatinib therapy administered for 3 years has been demonstrated to further increase recurrence-free survival and overall survival. The goal of this study was to assess the economic value of extending the duration of adjuvant imatinib therapy in high-risk patients in the Netherlands.Methods:A multistate Markov model was developed to simulate how patients’ clinical status after GIST excision evolves over time until death. The model structure encompassed four primary health states: free of recurrence, first GIST recurrence, second GIST recurrence, and death. Transition probabilities between the health states, data on medical care costs, and quality-of-life were obtained from published sources and from expert opinion.Results:The expected number of life years (or quality-adjusted life years, QALYs) was higher in the 3-year group than in the 1-year group, 8.91 (6.55) and 7.04 (5.18) years, respectively. In the 3-year and 1-year group, the expected total costs amounted to €120,195 and €79,361, of which, €74,631 (62%) and €27,619 (35%) were adjuvant therapy drug costs, respectively. The difference in health benefits, that is 1.87 life years or 1.37 QALYs, and costs, €40,835, resulted in incremental cost-effectiveness ratios (ICER) of €21,865 per life year gained, and €29,872 per QALY gained.Limitations:A limitation of the study was inherently related to the uncertainty around the predictions of RFS. Scenario analyses were conducted to test the sensitivity of different RFS predictions on the results.Conclusions:Delayed recurrence due to treatment with longer-term adjuvant imatinib therapy represents a cost-effective treatment option with an ICER below the generally accepted threshold in the Netherlands. |