Purpose Data on type 2 diabetes (T2D) risk after breast cancer (BC) could guide preventive strategies. Yet, studies had limitations regarding sample size, follow-up, and contemporary treatments. We evaluated the risk of T2D after BC overall, by cancer treatment, and compared with a matched cohort of cancer-free women. Methods We assembled a population-based cohort of early-stage BC patients aged ≥30 years diagnosed during 1996-2021 in Denmark. We created a comparison cohort of five cancer- and T2D-free women for each BC case, matched six months after BC diagnosis date on age and region. We followed both cohorts until T2D diagnosis, emigration, death, or December 31, 2022. We computed 5-year cumulative incidences and used Cox models to calculate time-varying adjusted hazard ratios (aHR) of T2D. Results Among 74,526 BC survivors and 372,630 matched cancer-free women, 5-year cumulative incidences of T2D were 3.8% (95%CI = 3.7-3.9) and 3.3% (95%CI = 3.3-3.4), respectively. The aHR of T2D was elevated but attenuated over follow-up (aHR5-years=1.20, 95%CI = 1.15-1.25, and aHR15-years=1.09, 95%CI = 1.05-1.12). Adjuvant endocrine therapy (aHR = 1.14; 95%CI = 1.10-1.19), aromatase inhibitors (aHR = 1.25; 95%CI = 1.18-1.32), and less so tamoxifen (aHR = 1.05; 95%CI = 0.99-1.11), were associated with elevated risk of T2D in women with BC vs cancer-free women. Among BC patients, chemotherapy (aHR = 1.10, 95%CI = 1.03-1.17) and radiation therapy (right-sided aHR = 1.18, 95%CI = 1.09-1.27 and left-sided aHR = 1.24, 95%CI = 1.15-1.33) were associated with increased T2D risk. Conclusion BC was associated with excess risk of T2D, though of lower magnitude than previously reported. The excess risk was temporary and related to BC treatment but could also be influenced by obesity and heightened T2D diagnostic activity.

中文翻译：

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乳腺癌治疗后 2 型糖尿病的风险：丹麦的一项基于人群的队列研究


目的 乳腺癌 （BC） 后 2 型糖尿病 （T2D） 风险的数据可以指导预防策略。然而，研究在样本量、随访和当代治疗方面存在局限性。我们通过癌症治疗评估了 BC 后 T2D 的总体风险，并与匹配的无癌症女性队列进行了比较。方法 我们收集了 1996-2021 年在丹麦诊断的年龄为 ≥30 岁的早期 BC 患者的人群队列。我们为每个 BC 病例创建了一个由 5 名无癌症和 T2D 女性组成的比较队列，在 BC 诊断日期后 6 个月根据年龄和地区进行匹配。我们跟踪了这两个队列，直到 T2D 诊断、移民、死亡或 2022 年 12 月 31 日。我们计算了 5 年累积发病率，并使用 Cox 模型计算了 T2D 的时变调整风险比 （aHR）。结果 在 74,526 名 BC 幸存者和 372,630 名匹配的无癌女性中，T2D 的 5 年累积发病率分别为 3.8% （95%CI = 3.7-3.9） 和 3.3% （95%CI = 3.3-3.4）。T2D 的 aHR 升高，但在随访中减弱 （aHR5 年=1.20,95% CI = 1.15-1.25，aHR15 年=1.09,95%CI = 1.05-1.12）。辅助内分泌治疗 （aHR = 1.14;95%CI = 1.10-1.19）、芳香化酶抑制剂 （aHR = 1.25;95%CI = 1.18-1.32） 和他莫昔芬 （aHR = 1.05;95%CI = 0.99-1.11） 与 BC 女性与无癌女性的 T2D 风险升高相关。在 BC 患者中，化疗 （aHR = 1.10,95%CI = 1.03-1.17） 和放疗 （右侧 aHR = 1.18,95%CI = 1.09-1.27 和左侧 aHR = 1.24,95%CI = 1.15-1.33） 与 T2D 风险增加相关。结论 BC 与 T2D 的超额风险相关，尽管其幅度低于以前报道的程度。 超额风险是暂时的，与 BC 治疗有关，但也可能受到肥胖和 T2D 诊断活动增加的影响。