Aim: To determine the change in the optimal chemotherapy utilization rate for early breast cancer patients in Australia following the recent publication of evidence showing that adjuvant endocrine therapy is not inferior to chemo-endocrine therapy in selected patients with early breast cancer.
Background: We had previously determined that 64% of Stage I and II breast cancer patients should receive at least one course of chemotherapy, according to the best available evidence at the time (1). In July 2018, new evidence from a prospective clinical trial (TAILORx) of 10,273 women found that adjuvant endocrine therapy is not inferior to chemo-endocrine therapy in patients with hormone receptor positive, HER2 negative, axillary node negative breast cancer and a mid-range recurrence score on 21 gene assay.
Methods: The existing model of optimal chemotherapy utilisation for early breast cancer was modified based on the new evidence from the TAILORx study. Branches were added to the existing model. Epidemiological data were identified for each new branch in the model and some of the existing data was updated. TreeAge software was used to construct the model and to calculate the optimal chemotherapy utilisation rate.
Results: When taking the latest evidence into account, the optimal chemotherapy utilization rate fell from 64% of all patients with early breast cancer to 54%. Our model shows that chemotherapy is indicated at least once in 54% of women presenting with early breast cancer.
Conclusions: Our model has shown that if the evidence from the TAILORx prospective trial is incorporated into clinical practice, then the optimal rate of chemotherapy utilisation in breast cancer will fall from 64% of all patients presenting with early breast cancer to 54%. This will result in significant cost savings from drug costs, costs associated with administration of chemotherapy and avoidance of hospitalisation due to toxicity.