Partial-breast radiotherapy after breast conservation surgery for women with early breast cancer (UK IMPORT LOW): 10-year outcomes from a multicentre, open-label, randomised, controlled, phase 3, non-inferiority trial.

We report outcomes after 10 years.

我们报告了10年后的结果。

Methods

IMPORT LOW was a randomised, open-label, multicentre, non-inferiority, phase 3 trial. Women were eligible if they were aged 50 years or older and had had breast conservation surgery for unifocal invasive ductal adenocarcinoma, pT1-2 (tumour size of ≤3 cm), N0-1 (none to three positive axillary nodes), grades 1-3, with microscopic margins of non-cancerous tissue of 2 mm or more.

IMPORT LOW 是一项随机、开放标签、多中心、非劣效性、III期试验。如果女性年龄在50岁或以上，并且已经接受了单灶性浸润性导管腺癌的乳腺保留手术，肿瘤大小为pT1-2（≤3厘米），N0-1（无到三个阳性腋窝淋巴结），分级1-3，显微镜下非癌组织边缘为2毫米或更多，那么她们就有资格参与。

Patients were ineligible if they had a previous malignancy of any kind (except non-melanomatous skin cancer), had undergone mastectomy, or had received neoadjuvant or concurrent adjuvant chemotherapy.

如果患者有任何类型的先前恶性肿瘤（除了非黑色素瘤皮肤癌）、已经接受了乳房切除术，或者已经接受了新辅助或同时辅助化疗，那么她们就不符合参与条件。

Patients were randomly assigned (1:1:1) by randomly permuted blocks to radiotherapy regimens of 40 Gy in 15 fractions to the whole breast (whole-breast group), 36 Gy in 15 fractions to the whole breast plus 40 Gy in 15 fractions to the partial breast (reduced-dose group), or 40 Gy in 15 fractions to the partial breast (partial-breast group).

患者按1:1:1的比例通过随机排列的区块随机分配到三种放疗方案：全乳腺接受40 Gy/15次照射（全乳腺组），全乳腺接受36 Gy/15次照射加部分乳腺接受40 Gy/15次照射（减量组），或部分乳腺接受40 Gy/15次照射（部分乳腺组）。

Participants were stratified by treatment centre, without masking.

参与者按治疗中心进行分层，未进行盲法处理。

The primary endpoint was IBTR. 10-year outcomes were analysed in the intention-to-treatpopulation.

主要终点是首次乳腺肿瘤复发（IBTR）。在意向治疗人群中分析了10年的结果。

Clinician-reported late adverse effects were evaluated in all participants with available data analysed according to allocated treatment.

所有有可用数据的参与者都根据分配的治疗评估了临床医生报告的晚期不良反应。

The study is registered in the ISRCTN registry (ISRCTN12852634) and is now complete.

该研究已在ISRCTN注册（ISRCTN12852634），现已完成。

Results

2018 patients were recruited between May 3, 2007, and Oct 5, 2010, from 30 radiotherapy centres in the UK and randomly assigned to the whole-breast group (n=675), reduced-dose group (n=674), or partial-breast group (n=669).

2018名患者在2007年5月3日至2010年10月5日期间，从英国的30个放射治疗中心招募，并随机分配到全乳腺组（n=675）、减量组（n=674）或部分乳腺组（n=669）。

Two participants subsequently withdrew consent.

两名参与者随后撤回了同意书。

Median age was 63 years (IQR 58-68). 854 (42%) of 2016 patients had grade 1 tumours, 959 (48%) had grade 2 tumours, and 200 (10%) had grade 3 tumours (three tumours were ungradable); 59 (3%) had node-positive disease.

中位年龄为63岁（四分位数间距58-68岁）。

Median follow-up was 120 months (IQR 119-122) for the whole-breast group, 121 months (IQR 120-122) for the reduced-dose group, and 120 months (IQR 119-122) for the partial-breast group.

全乳房组的中位随访时间为120个月（四分位数间距119-122），减少剂量组为121个月（四分位数间距120-122），部分乳房组为120个月（四分位数间距119-122）。

By 10 years, IBTR events were reported for 45 of 2016 participants: 17 of 674 in the whole-breast group, 11 of 673 in the reduced-dose group, and 17 of 669 in the partial-breast group, with cumulative incidenceof 2·8% (95% CI 1·8-4·5), 1·9% (1·1-3·5), and 3·0% (1·9-4·8), respectively.

在10年时，共有2016名参与者报告了45例IBTR事件：全乳房组674人中有17例，减少剂量组673人中有11例，部分乳房组669人中有17例，累积发生率分别为2.8%（95%置信区间1.8-4.5）、1.9%（1.1-3.5）和3.0%（1.9-4.8）。

The estimated absolute difference in 10-year IBTR incidencewas -1·02% (95% CI -1·98 to 0·99) for the reduced-dose group and 0·16% (-1·28 to 2·89) for the partial-breast group compared with the whole-breast group.

在10年局部乳腺肿瘤复发（IBTR）发生率的估计绝对差异中，减量组为-1.02%（95%置信区间-1.98至0.99），部分乳腺组为0.16%（-1.28至2.89），与全乳腺组相比。

Similar low levels of moderate or marked adverse effects were recorded for participants in all three groups in 10-year clinical assessments.

在10年的临床评估中，所有三组参与者的中度或明显不良反应水平均记录为相似的低水平。

Breast shrinkage had the highest incidence(30 [9%] of 321 in the whole-breast group, 28 [9%] of 322 in the reduced-dose group, and 22 [7%] of 333 in the partial-breast group).

在全乳组中，乳房缩小的发生率最高（321人中有30人[9%]），在减量组中为322人中有28人[9%]，在部分乳组中为333人中有22人[7%]。

interpretation

Long-term follow-up provides further evidence that partial-breast and reduced-dose radiotherapy are as safe and effective as whole-breast radiotherapy in patients with low-risk early breast cancer.

长期随访进一步证明，在低风险早期乳腺癌患者中，部分乳房和减量放疗与全乳放疗一样安全有效。

These results reaffirm the use of partial-breast radiotherapy delivered with intensity-modulated radiotherapy in this population as standard of care.

这些结果重申了在这一人群中使用强度调制放射治疗进行部分乳腺放射治疗作为护理标准的使用。

funding

Cancer Research UK.

英国癌症研究