ImportanceThe benefit of bilateral mastectomy for women with unilateral breast cancer in terms of deaths from breast cancer has not been shown.ObjectivesTo estimate the 20-year cumulative risk of breast cancer mortality among women with stage 0 to stage III unilateral breast cancer according to the type of initial surgery performed.Design, Settings, and ParticipantsThis cohort study used the Surveillance, Epidemiology, and End Results (SEER) Program registry database to identify women with unilateral breast cancer (invasive and ductal carcinoma in situ) who were diagnosed from 2000 to 2019. Three closely matched cohorts of equal size were generated using 1:1:1 matching according to surgical approach. The cohorts were followed up for 20 years for contralateral breast cancer and for breast cancer mortality. The analysis compared the 20-year cumulative risk of breast cancer mortality for women treated with lumpectomy vs unilateral mastectomy vs bilateral mastectomy. Data were analyzed from October 2023 to February 2024.ExposuresType of breast surgery performed (lumpectomy, unilateral mastectomy, or bilateral mastectomy).Main Outcomes and MeasuresContralateral breast cancer or breast cancer mortality during the 20-year follow-up period among the groups treated with lumpectomy vs unilateral mastectomy vs bilateral mastectomy.ResultsThe study sample included 661 270 women with unilateral breast cancer (mean [SD] age, 58.7 [11.3] years). After matching, there were 36 028 women in each of the 3 treatment groups. During the 20-year follow-up, there were 766 contralateral breast cancers observed in the lumpectomy group, 728 contralateral breast cancers in the unilateral mastectomy group, and 97 contralateral cancers in the bilateral mastectomy group. The 20-year risk of contralateral breast cancer was 6.9% (95% CI, 6.1%-7.9%) in the lumpectomy-unilateral mastectomy group. The cumulative breast cancer mortality was 32.1% at 15 years after developing a contralateral cancer and was 14.5% for those who did not develop a contralateral cancer (hazard ratio, 4.00; 95% CI, 3.52-4.54, using contralateral breast cancer as a time-dependent covariate). Deaths from breast cancer totaled 3077 women (8.54%) in the lumpectomy group, 3269 women (9.07%) in the unilateral mastectomy group, and 3062 women (8.50%) in the bilateral mastectomy group.Conclusions and RelevanceThis cohort study indicates that the risk of dying of breast cancer increases substantially after experiencing a contralateral breast cancer. Women with breast cancer treated with bilateral mastectomy had a greatly diminished risk of contralateral breast cancer; however, they experienced similar mortality rates as patients treated with lumpectomy or unilateral mastectomy.

中文翻译：

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双侧乳房切除术和乳腺癌死亡率


重要性尚未显示双侧乳房切除术对单侧乳腺癌女性在乳腺癌死亡方面的益处。 目的根据类型估计 0 期至 III 期单侧乳腺癌女性的 20 年累积乳腺癌死亡风险设计、设置和参与者本队列研究使用监测、流行病学和最终结果 (SEER) 计划注册数据库来识别 2000 年至 2019 年诊断出的单侧乳腺癌（浸润性和导管原位癌）女性根据手术方法使用 1:1:1 匹配生成三个大​​小相等的紧密匹配队列。对队列的对侧乳腺癌和乳腺癌死亡率进行了 20 年的随访。该分析比较了接受乳房肿瘤切除术、单侧乳房切除术和双侧乳房切除术治疗的女性的 20 年乳腺癌死亡累积风险。数据分析时间为 2023 年 10 月至 2024 年 2 月。 暴露 进行的乳房手术类型（肿块切除术、单侧乳房切除术或双侧乳房切除术）。 主要结果和措施 接受治疗的组中 20 年随访期间的对侧乳腺癌或乳腺癌死亡率肿瘤切除术与单侧乳房切除术与双侧乳房切除术。结果研究样本包括 661 270 名患有单侧乳腺癌的女性（平均 [SD] 年龄，58.7 [11.3] 岁）。匹配后，3 个治疗组各有 36 028 名女性。在20年的随访期间，肿瘤切除组观察到对侧乳腺癌766例，单侧乳房切除组观察到728例对侧乳腺癌，双侧乳房切除组观察到97例对侧乳腺癌。 肿瘤切除-单侧乳房切除组的 20 年对侧乳腺癌风险为 6.9%（95% CI，6.1%-7.9%）。患对侧癌症后 15 年，累积乳腺癌死亡率为 32.1%，未患对侧癌症的患者的累积乳腺癌死亡率为 14.5%（风险比，4.00；95% CI，3.52-4.54，以对侧乳腺癌作为时间）依赖协变量）。乳房肿块切除术组中有 3077 名女性（8.54%）死于乳腺癌，单侧乳房切除组有 3269 名女性（9.07%），双侧乳房切除组有 3062 名女性（8.50%）。结论和相关性本队列研究表明，乳腺癌死亡的风险在经历对侧乳腺癌后，死于乳腺癌的人数大幅增加。接受双侧乳房切除术治疗的乳腺癌女性大大降低了患对侧乳腺癌的风险；然而，他们的死亡率与接受乳房肿瘤切除术或单侧乳房切除术治疗的患者相似。