Background

Endocrine therapy is the mainstay treatment for breast cancer (BC) to reduce BC recurrence risk. During the first year of endocrine therapy use, nearly 30% of BC survivors are nonadherent, which may increase BC recurrence risk. This study is to examine the association between endocrine therapy adherence trajectories and BC recurrence risk in nonmetastatic BC survivors.

Methods

This retrospective cohort study included Medicare beneficiaries in the United States (US) with incident nonmetastatic BC followed by endocrine therapy initiation in 2010–2019 US Surveillance, Epidemiology, and End Results linked Medicare data. We calculated monthly fill-based proportion of days covered in the first year of endocrine therapy. We applied group-based trajectory models to identify distinct endocrine therapy adherence patterns. After the end of the first-year endocrine therapy trajectory measurement period, we estimated the risk of time to first treated BC recurrence within 4 years using Cox proportional hazards models.

Results

We identified 5 trajectories of adherence to endocrine therapy in BC Stages 0–I subgroup (n = 28,042) and in Stages II–III subgroup (n = 7781). A trajectory of discontinuation before 6 months accounted for 7.0% in Stages 0–I and 5.8% in Stages II–III subgroups, and this trajectory was associated with an increased treated BC recurrence risk compared to nearly perfect adherence (Stages 0–I: adjusted hazard [aHR] = 1.84, 95% CI = 1.46–2.33; Stages II–III: aHR = 1.38, 95% CI = 1.07–1.77).

Conclusions

Nearly 7% of BC survivors who discontinued before completing 6 months of treatment was associated with an increased treated BC recurrence risk compared to those with nearly perfect adherence among Medicare nonmetastatic BC survivors.

中文翻译：

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美国非转移性乳腺癌幸存者中内分泌治疗依从性轨迹与已治疗乳腺癌复发风险之间的关联

背景

内分泌治疗是乳腺癌 (BC) 的主要治疗方法，可降低 BC 复发风险。在使用内分泌治疗的第一年，近 30% 的 BC 幸存者不依从治疗，这可能会增加 BC 复发风险。本研究旨在探讨非转移性 BC 幸存者的内分泌治疗依从轨迹与 BC 复发风险之间的关联。

方法

这项回顾性队列研究包括美国 (US) 的 Medicare 受益人，这些受益人在 2010-2019 年美国监测、流行病学和最终结果中发生非转移性 BC，随后开始内分泌治疗，这些数据与 Medicare 数据相关。我们计算了内分泌治疗第一年中每月基于填充的天数比例。我们应用基于群体的轨迹模型来识别不同的内分泌治疗依从模式。第一年内分泌治疗轨迹测量期结束后，我们使用 Cox 比例风险模型估计了 4 年内首次治疗 BC 复发的风险。

结果

我们确定了 BC 0-I 期亚组 ( n  = 28,042) 和 II-III 期亚组 ( n  = 7781)的 5 条坚持内分泌治疗的轨迹。 6 个月前停药的轨迹在 0-I 期亚组中占 7.0%，在 II-III 期亚组中占 5.8%，与近乎完美的依从性相比，该轨迹与治疗 BC 复发风险增加相关（0-I 期：调整后）危险 [aHR] = 1.84，95% CI = 1.46–2.33；II-III 阶段：aHR = 1.38，95% CI = 1.07–1.77）。

结论

与 Medicare 非转移性 BC 幸存者中几乎完美依从的患者相比，近 7% 在完成 6 个月治疗之前停止治疗的 BC 幸存者与治疗后 BC 复发风险增加相关。