对于乳腺癌患者来说，化疗开始的延迟与复发和生存存在不利相关。我们在社区早期乳腺癌女性队列中评估了与延迟化疗开始相关的患者层面因素，包括诊断和手术。在最佳乳腺癌化疗剂量研究中，我们确定了 2004 年至 2019 年间在美国两个综合医疗保健服务系统中被诊断患有 I-IIIA 期乳腺癌的 34,109 名女性的队列。我们使用逻辑回归来计算比值比 (OR) 和 95%置信区间（CI），以确定与诊断后（≥90天）和手术（≥60天）开始化疗延迟相关的患者因素。在 10,968 名接受辅助化疗的女性中，21.1% 的女性在诊断后延迟开始化疗，21.3% 的女性在手术后延迟开始化疗。年龄较大、非西班牙裔黑人和西班牙裔种族和民族以及 ER 和/或 PR 疾病与诊断和手术后延迟开始化疗的可能性增加有关。 2012 年至 2019 年（对比 2005 年至 2011 年）诊断的肿瘤级别较高、肿瘤尺寸较大的患者出现延误的可能性较小。其他因素与延迟的可能性较高有关，特别是诊断（早期阶段、乳房切除术与保乳手术）或手术（合并症较高、淋巴结数量增加）。被诊断患有乳腺癌的女性进展和复发风险最高，在诊断和手术后延迟开始化疗的可能性较小。了解患者因素之外的化疗延迟的原因可能对于降低乳腺癌复发和进展的风险可能很重要。© 2024 UICC。

For patients with breast cancer, delays in chemotherapy initiation have been adversely associated with recurrence and survival. We evaluated patient-level factors associated with delayed chemotherapy initiation, from both diagnosis and surgery, in a community-based cohort of women with early-stage breast cancer. For the Optimal Breast Cancer Chemotherapy Dosing study, we identified a cohort of 34,109 women diagnosed with stage I-IIIA breast cancer at two U.S. integrated healthcare delivery systems between 2004 and 2019. We used logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI) to identify patient factors associated with delays in chemotherapy initiation after diagnosis (≥90 days) and surgery (≥60 days). Among 10,968 women receiving adjuvant chemotherapy, 21.1% experienced delays in chemotherapy initiation after diagnosis and 21.3% after surgery. Older age, non-Hispanic Black and Hispanic race and ethnicity, and ER+ and/or PR+ disease were associated with increased likelihood of delays to chemotherapy initiation after diagnosis and surgery. People diagnosed in 2012-2019 (vs. 2005-2011), with a higher grade and larger tumor size were less likely to experience delays. Other factors were associated with a higher likelihood of delays specifically from diagnosis (earlier stage, mastectomy vs. breast-conserving surgery), or surgery (higher comorbidity, increased nodal number). Women diagnosed with breast cancer who were at highest risk of progression and recurrence were less likely to experience delays in chemotherapy initiation after diagnosis and surgery. Understanding reasons for chemotherapy delays beyond patient factors may be potentially important to reduce risk of breast cancer recurrence and progression.© 2024 UICC.