Conclusions
ER-positive
Conventional ITT analysis is a valid and universally accepted analytic approach to test two treatment strategies, but it does not control for potential biases due to treatment discontinuation. Additional analyses should be considered in long-term trials with substantial non-adherence to randomized treatment, so as to assess the effect of non-adherence on the estimate from the ITT analysis. In the context of the TAM01 trial, adjusting for treatment adherence using the MSM and RPSFT methods, reveals that long-term tamoxifen has a greater protective effect on iDFS and OS in ER-positive early BC patients. These structural methods emphasize the benefit of adhering to hormonotherapy in hormone-receptor positive early BC.