Smilow Cancer Center, Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut.
Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut.
JAMA Oncol. 2017 Aug 1;3(8):1060-1068. doi: 10.1001/jamaoncol.2016.6948.
The use of a radiotherapy (RT) boost to the tumor bed after whole-breast RT (WBRT) for ductal carcinoma in situ (DCIS) is largely extrapolated from invasive cancer data, but robust evidence specific to DCIS is lacking.
To compare ipsilateral breast tumor recurrence (IBTR) in women with DCIS treated with vs without the RT boost after breast-conserving surgery and WBRT.
DESIGN, SETTING, AND PARTICIPANTS: This retrospective analysis pooled deidentified patient-level data from 10 academic institutions in the United States, Canada, and France from January 1, 1980, through December 31, 2010. All patients had newly diagnosed pure DCIS (no microinvasion), underwent breast-conserving surgery, and received WBRT with or without the boost with a minimum of 5 years of follow-up required for inclusion in the analysis. Given the limited events after WBRT, an a priori power analysis was conducted to estimate the DCIS sample size needed to detect the anticipated benefit of the boost. Data were uniformly recoded at the host institution and underwent primary and secondary reviews before analysis. Sample size calculations (ratio of patients who received the boost dose to those who did not, 2:1; α = .05; power = 80%) estimated that 2982 cases were needed to detect a difference of at least 3%. The final analysis included 4131 patients (2661 in the boost group and 1470 in the no-boost group) with a median follow-up of 9 years and media boost dose of 14 Gy. Data were collected from July 2011 through February 2014 and analyzed from March 2014 through August 2015.
Radiotherapy boost vs no boost.
Ipsilateral breast tumor recurrence.
The analysis included 4131 patients (median [SD] age, 56.1 [10.9] years; range, 24-88 years). Patients with positive margins, unknown estrogen receptor status, and comedo necrosis were more likely to have received an RT boost. For the entire cohort, the boost was significantly associated with lower IBTR (hazard ratio [HR], 0.73; 95% CI, 0.57-0.94; P = .01) and with IBTR-free survival (boost vs no-boost groups) of 97.1% (95% CI, 0.96-0.98) vs 96.3% (95% CI, 0.95-0.97) at 5 years, 94.1% (95% CI, 0.93-0.95) vs 92.5% (95% CI, 0.91-0.94) at 10 years, and 91.6% (95% CI, 0.90-0.93) vs 88.0% (95% CI, 0.85-0.91) at 15 years. On multivariable analysis accounting for confounding factors, the boost remained significantly associated with reduced IBTR (HR compared with no boost, 0.68; 95% CI, 0.50-0.91; P = .01) independent of age and tamoxifen citrate use.
This patient-level analysis suggests that the RT boost confers a statistically significant benefit in decreasing IBTR across all DCIS age groups, similar to that seen in patients with invasive breast cancer. These findings suggest that a DCIS RT boost to the tumor bed could be considered to provide an added incremental benefit in decreasing IBTR after a shared discussion between the patient and her radiation oncologist.
在全乳放射治疗（WBRT）后对肿瘤床进行放射治疗（RT）增敏主要是从浸润性癌症数据中推断出来的，但缺乏针对 DCIS 的可靠证据。
比较接受保乳手术后和 WBRT 后接受 DCIS 治疗的女性中，使用与不使用 RT 增敏的同侧乳腺肿瘤复发（IBTR）情况。
设计、地点和参与者：这是一项回顾性分析，从美国、加拿大和法国的 10 个学术机构中汇集了经过身份识别的患者水平数据，时间为 1980 年 1 月 1 日至 2010 年 12 月 31 日。所有患者均为新发纯 DCIS（无微浸润），接受保乳手术，且均接受 WBRT 治疗，其中一部分患者接受 RT 增敏，最低随访时间为 5 年，以纳入分析。鉴于 WBRT 后事件有限，进行了一项事先的功效分析，以估算需要检测增敏益处的 DCIS 样本量。在分析前，数据在宿主机构中统一进行了重新编码，并进行了初步和二次审查。样本量计算（接受增敏剂量的患者与未接受增敏剂量的患者之比为 2:1；α=0.05；功效=80%）估计需要 2982 例病例来检测至少 3%的差异。最终分析纳入了 4131 例患者（增敏组 2661 例，非增敏组 1470 例），中位随访时间为 9 年，中位增敏剂量为 14 Gy。数据于 2011 年 7 月至 2014 年 2 月收集，并于 2014 年 3 月至 2015 年 8 月进行分析。
放射治疗增敏与不增敏。
同侧乳腺肿瘤复发。
分析纳入了 4131 例患者（中位[标准差]年龄为 56.1[10.9]岁；范围为 24-88 岁）。有切缘阳性、雌激素受体状态未知和粉刺样坏死的患者更有可能接受 RT 增敏。对于整个队列，增敏与较低的 IBTR 显著相关（风险比[HR]，0.73；95%CI，0.57-0.94；P=0.01），并且在 5 年时，增敏组的 IBTR 无复发生存率（增敏组与非增敏组）为 97.1%（95%CI，0.96-0.98），而非增敏组为 96.3%（95%CI，0.95-0.97）；在 10 年时，增敏组为 94.1%（95%CI，0.93-0.95），而非增敏组为 92.5%（95%CI，0.91-0.94）；在 15 年时，增敏组为 91.6%（95%CI，0.90-0.93），而非增敏组为 88.0%（95%CI，0.85-0.91）。在多变量分析中，考虑到混杂因素，增敏与降低 IBTR 仍显著相关（与未增敏相比，HR 为 0.68；95%CI，0.50-0.91；P=0.01），独立于年龄和他莫昔芬枸橼酸盐的使用。
这项患者水平分析表明，RT 增敏在所有 DCIS 年龄组中均显著降低 IBTR，与浸润性乳腺癌患者相似。这些发现表明，在与患者和她的放射肿瘤学家进行共同讨论后，对肿瘤床进行 DCIS RT 增敏可以提供额外的、渐进的降低 IBTR 的益处。
