How do you decide for which high-risk post-menopausal women to extend adjuvant endocrine therapy after completing 5 years?

Ever since the MA.17R data was presented by Paul Goss at the ASCO plenary session in 2016 and its simultaneous publication in NEJM, extended aromatase inhibitor therapy has been a topic of great interest. This study did show an nearly 4% absolute benefit for the longer duration as far as DFS was concerned but again no OS advantage. Six months later, the DATA and IDEAL studies were presented at SABCS which did not seem to show an advantage. These conflicting data made it clear that there is no “one size fits all” when it comes to extended duration of aromatase inhibitors. Subset analyses in all these studies, as also the EBCTCG meta-analysis and the ABCSG-16 study did show that as the nodal burden increased, there was a trend towards DFS...

The recent EBCTCG meta analysis suggested a bigger benefit as the nodal burden increased (especially N2). Also more in breast recurrences than distant events were prevented so women who do breast conservation may benefit more. The CTS5 online calculator or a genomic test such as the BCI assay can also help with estimating risk. As for the duration if a high risk patient is tolerating therapy I try to do 5 years if the patient is willing. Most of the trials including the recent Japanese AERAS study did longer treatments. Also extended treatment durations may have longer carryover effects that could emerge with additional follow up.