Five-Year Adjuvant Endocrine Therapy Adherence Trajectories Among Women With Breast Cancer: A Nationwide French Study Using Administrative Data

•A large proportion of women are nonadherent to adjuvant endocrine therapy.•Seventy percent of women will have optimal adherence for 5 years.•Extreme age categories and switching adjuvant endocrine therapy were associated with nonadherence trajectories.•Four percent of women followed a “continuous suboptimal adherence trajectory,” previously unidentified in the literature.