更年期泌尿生殖综合征可以通过阴道雌激素治疗来治疗。然而，人们对乳腺癌患者阴道雌激素治疗的安全性存在担忧。 确定使用阴道雌激素治疗的女性乳腺癌患者与未使用阴道雌激素治疗的女性乳腺癌患者相比，乳腺癌特异性死亡率的风险是否更高激素替代疗法 (HRT)。这项队列研究分析了 2 个大型队列，苏格兰和威尔士各一个，对象是 40 至 79 岁新诊断乳腺癌的女性。这些基于人群的队列是从苏格兰 2010 年至 2017 年和威尔士 2000 年至 2016 年的国家癌症登记记录中确定的，并跟踪乳腺癌特异性死亡率直至 2020 年。如果女性之前有癌症诊断，则被排除在外（除非非黑色素瘤皮肤癌）。数据分析于 2022 年 8 月至 2023 年 8 月期间进行。阴道雌激素治疗（包括阴道片剂和乳膏）的使用情况是根据苏格兰队列处方信息系统的药房配药记录和威尔士队列的全科医生处方记录确定的。主要结局是乳腺癌特异性死亡率的时间，该死亡率是从国家死亡率记录中获得的。使用时间依赖性 Cox 比例风险回归模型计算乳腺癌特异性死亡率的风险比 (HR) 和 95% CI，比较阴道雌激素治疗使用者与 HRT 未使用者并调整混杂因素，包括癌症分期和分级。 2 个队列包括 49237 名患有乳腺癌的女性（年龄在 40 至 79 岁之间）和 5795 例乳腺癌相关死亡。百分之五的乳腺癌患者在乳腺癌诊断后使用阴道雌激素治疗。与非 HRT 使用者相比，阴道雌激素治疗使用者中，没有证据表明在完全调整的汇总模型中乳腺癌特异性死亡率风险更高（HR，0.77；95% CI，0.63-0.94）。有证据表明，与不使用激素替代疗法的患者相比，使用阴道雌激素治疗的患者的早期乳腺癌特异性死亡率有所增加。这一发现可能会给临床医生带来一些安慰，并支持指南建议对患有乳腺癌和泌尿生殖系统症状的患者可以考虑阴道雌激素治疗。

Genitourinary syndrome of menopause can be treated with vaginal estrogen therapy. However, there are concerns about the safety of vaginal estrogen therapy in patients with breast cancer.To determine whether the risk of breast cancer-specific mortality was higher in females with breast cancer who used vaginal estrogen therapy vs females with breast cancer who did not use hormone replacement therapy (HRT).This cohort study analyzed 2 large cohorts, one each in Scotland and Wales, of females aged 40 to 79 years with newly diagnosed breast cancer. These population-based cohorts were identified from national cancer registry records from 2010 to 2017 in Scotland and from 2000 to 2016 in Wales and were followed up for breast cancer-specific mortality until 2020. Females were excluded if they had a previous cancer diagnosis (except nonmelanoma skin cancer). Data analysis was performed between August 2022 and August 2023.Use of vaginal estrogen therapy, including vaginal tablets and creams, was ascertained from pharmacy dispensing records of the Prescribing Information System for the Scotland cohort and from general practice prescription records for the Wales cohort.The primary outcome was time to breast cancer-specific mortality, which was obtained from national mortality records. Time-dependent Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% CIs for breast cancer-specific mortality, comparing vaginal estrogen therapy users with HRT nonusers and adjusting for confounders, including cancer stage and grade.The 2 cohorts comprised 49 237 females with breast cancer (between 40 and 79 years of age) and 5795 breast cancer-specific deaths. Five percent of patients with breast cancer used vaginal estrogen therapy after breast cancer diagnosis. In vaginal estrogen therapy users compared with HRT nonusers, there was no evidence of a higher risk of breast cancer-specific mortality in the pooled fully adjusted model (HR, 0.77; 95% CI, 0.63-0.94).Results of this study showed no evidence of increased early breast cancer-specific mortality in patients who used vaginal estrogen therapy compared with patients who did not use HRT. This finding may provide some reassurance to prescribing clinicians and support the guidelines suggesting that vaginal estrogen therapy can be considered in patients with breast cancer and genitourinary symptoms.