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Background: We previously reported the 5-year results of the phase 3 IBCSG 23-01 trial comparing disease-free survival in patients with breast cancer with one or more micrometastatic (≤2 mm) sentinel nodes randomly assigned to either axillary dissection or no axillary dissection. The results showed no difference in disease-free survival between the groups and showed non-inferiority of no axillary dissection relative to axillary dissection. The current analysis presents the results of the study after a median follow-up of 9·7 years (IQR 7·8-12·7).Methods: In this multicentre, randomised, controlled, open-label, non-inferiority, phase 3 trial, participants were recruited from 27 hospitals and cancer centres in nine countries. Eligible women could be of any age with clinical, mammographic, ultrasonographic, or pathological diagnosis of breast cancer with largest lesion diameter of 5 cm or smaller, and one or more metastatic sentinel nodes, all of which were 2 mm or smaller and with no extracapsular extension. Patients were randomly assigned (1:1) before surgery (mastectomy or breast-conserving surgery) to no axillary dissection or axillary dissection using permuted blocks generated by a web-based congruence algorithm, with stratification by centre and menopausal status. The protocol-specified primary endpoint was disease-free survival, analysed in the intention-to-treat population (as randomly assigned). Safety was assessed in all randomly assigned patients who received their allocated treatment (as treated). We did a one-sided test for non-inferiority of no axillary dissection by comparing the observed hazard ratios (HRs) for disease-free survival with a margin of 1·25. This 10-year follow-up analysis was not prespecified in the trial's protocol and thus was not adjusted for multiple, sequential testing. This trial is registered with ClinicalTrials.gov, number NCT00072293.Findings: Between April 1, 2001, and Feb 8, 2010, 6681 patients were screened and 934 randomly assigned to no axillary dissection (n=469) or axillary dissection (n=465). Three patients were ineligible and were excluded from the trial after randomisation. Disease-free survival at 10 years was 76·8% (95% CI 72·5-81·0) in the no axillary dissection group, compared with 74·9% (70·5-79·3) in the axillary dissection group (HR 0·85, 95% CI 0·65-1·11; log-rank p=0·24; p=0·0024 for non-inferiority). Long-term surgical complications included lymphoedema of any grade in 16 (4%) of 453 patients in the no axillary dissection group and 60 (13%) of 447 in the axillary dissection group, sensory neuropathy of any grade in 57 (13%) in the no axillary dissection group versus 85 (19%) in the axillary dissection group, and motor neuropathy of any grade (14 [3%] in the no axillary dissection group vs 40 [9%] in the axillary dissection group). One serious adverse event (postoperative infection and inflamed axilla requiring hospital admission) was attributed to axillary dissection; the event resolved without sequelae.Interpretation: The findings of the IBCSG 23-01 trial after a median follow-up of 9·7 years (IQR 7·8-12·7) corroborate those obtained at 5 years and are consistent with those of the 10-year follow-up analysis of the Z0011 trial. Together, these findings support the current practice of not doing an axillary dissection when the tumour burden in the sentinel nodes is minimal or moderate in patients with early breast cancer.Funding: International Breast Cancer Study Group. [ABSTRACT FROM AUTHOR]

Background: In the randomised, phase 3 equivalence trial on electron intraoperative radiotherapy (ELIOT), accelerated partial breast irradiation (APBI) with the use of intraoperative radiotherapy was associated with a higher rate of ipsilateral breast tumour recurrence (IBTR) than whole-breast irradiation (WBI) in patients with early-stage breast cancer. Here, we aimed to examine the planned long-term recurrence and survival outcomes from the ELIOT trial.Methods: This single-centre, randomised, phase 3 equivalence trial was done at the European Institute of Oncology (Milan, Italy). Eligible women, aged 48-75 years with a clinical diagnosis of a unicentric breast carcinoma with an ultrasound diameter not exceeding 25 mm, clinically negative axillary lymph nodes, and who were suitable for breast-conserving surgery, were randomly assigned (1:1) via a web-based system, with a random permuted block design (block size of 16) and stratified by clinical tumour size, to receive post-operative WBI with conventional fractionation (50 Gy given as 25 fractions of 2 Gy, plus a 10 Gy boost), or 21 Gy intraoperative radiotherapy with electrons (ELIOT) in a single dose to the tumour bed during surgery. The trial was open label and no-one was masked to treatment group assignment. The primary endpoint was the occurrence of IBTR. The trial was designed assuming a 5-year IBTR rate of 3% in the WBI group and equivalence of the two groups, if the 5-year IBTR rate in the ELIOT group did not exceed a 2·5 times excess, corresponding to 7·5%. Overall survival was the secondary endpoint. The main analysis was done by intention to treat. The cumulative incidence of IBTR events and overall survival were assessed at 5, 10, and 15 years of follow-up. This trial is registered with ClinicalTrials.gov, NCT01849133.Findings: Between Nov 20, 2000, and Dec 27, 2007, 1305 women were enrolled and randomly assigned: 654 to the WBI group and 651 to the ELIOT group. After a median follow-up of 12·4 years (IQR 9·7-14·7), 86 (7%) patients developed IBTR, with 70 (11%) cases in the ELIOT group and 16 (2%) in the WBI group, corresponding to an absolute excess of 54 IBTRs in the ELIOT group (HR 4·62, 95% CI 2·68-7·95, p<0·0001). In the ELIOT group, the 5-year IBTR rate was 4·2% (95% CI 2·8-5·9), the 10-year rate was 8·1% (6·1-10·3), and the 15-year rate was 12·6% (9·8-15·9). In the WBI group, the 5-year IBTR rate was 0·5% (95% CI 0·1-1·3), the 10-year rate was 1·1% (0·5-2·2), and the 15-year rate was 2·4% (1·4-4·0). At final follow-up on March 11, 2019, 193 (15%) women had died from any cause, with no difference between the two groups (98 deaths in the ELIOT group vs 95 in the WBI group; HR 1·03, 95% CI 0·77-1·36, p=0·85). In the ELIOT group, the overall survival rate was 96·8% (95% CI 95·1-97·9) at 5 years, 90·7% (88·2-92·7) at 10 years, and 83·4% (79·7-86·4) at 15 years; and in the WBI group, the overall survival rate was 96·8% (95·1-97·9) at 5 years, 92·7% (90·4-94·4) at 10 years, and 82·4% (78·5-85·6) at 15 years. We did not collect long-term data on adverse events.Interpretation: The long-term results of this trial confirmed the higher rate of IBTR in the ELIOT group than in the WBI group, without any differences in overall survival. ELIOT should be offered to selected patients at low-risk of IBTR.Funding: Italian Association for Cancer Research, Jacqueline Seroussi Memorial Foundation for Cancer Research, Umberto Veronesi Foundation, American Italian Cancer Foundation, The Lombardy Region, and Italian Ministry of Health. [ABSTRACT FROM AUTHOR]

Background: The MINDACT trial showed excellent 5-year distant metastasis-free survival of 94·7% (95% CI 92·5-96·2) in patients with breast cancer of high clinical and low genomic risk who did not receive chemotherapy. We present long-term follow-up results together with an exploratory analysis by age.Methods: MINDACT was a multicentre, randomised, phase 3 trial done in 112 academic and community hospitals in nine European countries. Patients aged 18-70 years, with histologically confirmed primary invasive breast cancer (stage T1, T2, or operable T3) with up to three positive lymph nodes, no distant metastases, and a WHO performance status of 0-1 were enrolled and their genomic risk (using the MammaPrint 70-gene signature) and clinical risk (using a modified version of Adjuvant! Online) were determined. Patients with low clinical and low genomic risk results did not receive chemotherapy, and patients with high clinical and high genomic risk did receive chemotherapy (mostly anthracycline-based or taxane-based, or a combination thereof). Patients with discordant risk results (ie, patients with high clinical risk but low genomic risk, and those with low clinical risk but high genomic risk) were randomly assigned (1:1) to receive chemotherapy or not based on either the clinical risk or the genomic risk. Randomisation was done centrally and used a minimisation technique that was stratified by institution, risk group, and clinical-pathological characteristics. Treatment allocation was not masked. The primary endpoint was to test whether the distant metastasis-free survival rate at 5 years in patients with high clinical risk and low genomic risk not receiving chemotherapy had a lower boundary of the 95% CI above the predefined non-inferiority boundary of 92%. In the primary test population of patients with high clinical risk and low genomic risk who adhered to the treatment allocation of no chemotherapy and had no change in risk post-enrolment. Here, we present updated follow-up as well as an exploratory analysis of a potential age effect (≤50 years vs >50 years) and an analysis by nodal status for patients with hormone receptor-positive and HER2-negative disease. These analyses were done in the intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT00433589, and the European Clinical Trials database, EudraCT2005-002625-31. Recruitment is complete and further long-term follow-up is ongoing.Findings: Between Feb 8, 2007, and July 11, 2011, 6693 patients were enrolled. On Feb 26, 2020, median follow-up was 8·7 years (IQR 7·8-9·7). The updated 5-year distant metastasis-free survival rate for patients with high clinical risk and low genomic risk receiving no chemotherapy (primary test population, n=644) was 95·1% (95% CI 93·1-96·6), which is above the predefined non-inferiority boundary of 92%, supporting the previous analysis and proving MINDACT as a positive de-escalation trial. Patients with high clinical risk and low genomic risk were randomly assigned to receive chemotherapy (n=749) or not (n=748); this was the intention-to-treat population. The 8-year estimates for distant metastasis-free survival in the intention-to-treat population were 92·0% (95% CI 89·6-93·8) for chemotherapy versus 89·4% (86·8-91·5) for no chemotherapy (hazard ratio 0·66; 95% CI 0·48-0·92). An exploratory analysis confined to the subset of patients with hormone receptor-positive, HER2-negative disease (1358 [90.7%] of 1497 randomly assigned patients, of whom 676 received chemotherapy and 682 did not) shows different effects of chemotherapy administration on 8-year distant metastasis-free survival according to age: 93·6% (95% CI 89·3-96·3) with chemotherapy versus 88·6% (83·5-92·3) without chemotherapy in 464 women aged 50 years or younger (absolute difference 5·0 percentage points [SE 2·8, 95% CI -0·5 to 10·4]) and 90·2% (86·8-92·7) versus 90·0% (86·6-92·6) in 894 women older than 50 years (absolute difference 0·2 percentage points [2·1, -4·0 to 4·4]). The 8-year distant metastasis-free survival in the exploratory analysis by nodal status in these patients was 91·7% (95% CI 88·1-94·3) with chemotherapy and 89·2% (85·2-92·2) without chemotherapy in 699 node-negative patients (absolute difference 2·5 percentage points [SE 2·3, 95% CI -2·1 to 7·2]) and 91·2% (87·2-94·0) versus 89·9% (85·8-92·8) for 658 patients with one to three positive nodes (absolute difference 1·3 percentage points [2·4, -3·5 to 6·1]).Interpretation: With a more mature follow-up approaching 9 years, the 70-gene signature shows an intact ability of identifying among women with high clinical risk, a subgroup, namely patients with a low genomic risk, with an excellent distant metastasis-free survival when treated with endocrine therapy alone. For these women the magnitude of the benefit from adding chemotherapy to endocrine therapy remains small (2·6 percentage points) and is not enhanced by nodal positivity. However, in an underpowered exploratory analysis this benefit appears to be age-dependent, as it is only seen in women younger than 50 years where it reaches a clinically relevant threshold of 5 percentage points. Although, possibly due to chemotherapy-induced ovarian function suppression, it should be part of informed, shared decision making. Further study is needed in younger women, who might need reinforced endocrine therapy to forego chemotherapy.Funding: European Commission Sixth Framework Programme. [ABSTRACT FROM AUTHOR]

Background: HER2-positive breast cancers usually contain large amounts of T-cell infiltrate. We hypothesised that trastuzumab resistance in HER2-positive breast cancer could be mediated by immune mechanisms. We assessed the safety and anti-tumour activity of pembrolizumab, a programmed cell death protein 1 (PD-1) inhibitor, added to trastuzumab in trastuzumab-resistant, advanced HER2-positive breast cancer.Methods: We did this single-arm, multicentre, phase 1b-2 trial in 11 centres based in five countries. Eligible participants were women aged 18 years or older, who had advanced, histologically confirmed, HER2-positive breast cancer; documented progression during previous trastuzumab-based therapy; an Eastern Cooperative Oncology Group performance status of 0 or 1; and a formalin-fixed, paraffin-embedded metastatic tumour biopsy for central assessment of programmed cell death 1 ligand 1 (PD-L1) status. In phase 1b, we enrolled patients with PD-L1-positive tumours in a 3 + 3 dose-escalation of intravenous pembrolizumab (2 mg/kg and 10 mg/kg, every 3 weeks) plus 6 mg/kg of intravenous trastuzumab. The primary endpoint of the phase 1b study was the incidence of dose-limiting toxicity and recommended phase 2 dose; however, a protocol amendment on Aug 28, 2015, stipulated a flat dose of pembrolizumab of 200 mg every 3 weeks in all Merck-sponsored trials. In phase 2, patients with PD-L1-positive and PD-L1-negative tumours were enrolled in parallel cohorts and received the flat dose of pembrolizumab plus standard trastuzumab. The primary endpoint of the phase 2 study was the proportion of PD-L1-positive patients achieving an objective response. This trial is registered in ClinicalTrials.gov, number NCT02129556, and with EudraCT, number 2013-004770-10, and is closed.Findings: Between Feb 2, 2015, and April 5, 2017, six patients were enrolled in phase 1b (n=3 received 2 mg/kg pembrolizumab, n=3 received 10 mg/kg pembrolizumab) and 52 patients in phase 2 (n=40 had PD-L1-positive tumours, n=12 had PD-L1-negative tumours). The data cutoff for this analysis was Aug 7, 2017. During phase 1b, there were no dose-limiting toxicities in the dose cohorts tested. Median follow-up for the phase 2 cohort was 13·6 months (IQR 11·6-18·4) for patients with PD-L1-positive tumours, and 12·2 months (7·9-12·2) for patients with PD-L1-negative tumours. Six (15%, 90% CI 7-29) of 40 PD-L1-positive patients achieved an objective response. There were no objective responders among the PD-L1-negative patients. The most common treatment-related adverse event of any grade was fatigue (12 [21%] of 58 patients). Grade 3-5 adverse events occurred in 29 (50%) of patients, treatment-related grade 3-5 adverse events occurred in 17 (29%), and serious adverse events occurred in 29 (50%) patients. The most commonly occurring serious adverse events were dyspnoea (n=3 [5%]), pneumonitis (n=3 [5%]), pericardial effusion (n=2 [3%]), and upper respiratory infection (n=2 [3%]). There was one treatment-related death due to Lambert-Eaton syndrome in a PD-L1-negative patient during phase 2.Interpretation: Pembrolizumab plus trastuzumab was safe and showed activity and durable clinical benefit in patients with PD-L1-positive, trastuzumab-resistant, advanced, HER2-positive breast cancer. Further studies in this breast cancer subtype should focus on a PD-L1-positive population and be done in less heavily pretreated patients.Funding: Merck, International Breast Cancer Study Group. [ABSTRACT FROM AUTHOR]

Background: Despite the acknowledged sex-related dimorphism in immune system response, little is known about the effect of patients' sex on the efficacy of immune checkpoint inhibitors as cancer treatments. We did a systematic review and meta-analysis to assess the heterogeneity of immune checkpoint inhibitor efficacy between men and women.Methods: We systematically searched PubMed, MEDLINE, Embase, and Scopus, from database inception to Nov 30, 2017, for randomised controlled trials of immune checkpoint inhibitors (inhibitors of PD-1, CTLA-4, or both) that had available hazard ratios (HRs) for death according to patients' sex. We also reviewed abstracts and presentations from all major conference proceedings. We excluded non-randomised trials and considered only papers published in English. The primary endpoint was to assess the difference in efficacy of immune checkpoint inhibitors between men and women, measured in terms of the difference in overall survival log(HR) reported in male and female study participants. We calculated the pooled overall survival HR and 95% CI in men and women using a random-effects model, and assessed the heterogeneity between the two estimates using an interaction test.Findings: Of 7133 studies identified in our search, there were 20 eligible randomised controlled trials of immune checkpoint inhibitors (ipilimumab, tremelimumab, nivolumab, or pembrolizumab) that reported overall survival according to patients' sex. Overall, 11 351 patients with advanced or metastatic cancers (7646 [67%] men and 3705 [33%] women) were included in the analysis; the most common types of cancer were melanoma (3632 [32%]) and non-small-cell lung cancer (3482 [31%]). The pooled overall survival HR was 0·72 (95% CI 0·65-0·79) in male patients treated with immune checkpoint inhibitors, compared with men treated in control groups. In women treated with immune checkpoint inhibitors, the pooled overall survival HR compared with control groups was 0·86 (95% CI 0·79-0·93). The difference in efficacy between men and women treated with immune checkpoint inhibitors was significant (p=0·0019).Interpretation: Immune checkpoint inhibitors can improve overall survival for patients with advanced cancers such as melanoma and non-small-cell lung cancer, but the magnitude of benefit is sex-dependent. Future research should guarantee greater inclusion of women in trials and focus on improving the effectiveness of immunotherapies in women, perhaps exploring different immunotherapeutic approaches in men and women.Funding: None. [ABSTRACT FROM AUTHOR]

Background: In the neoadjuvant setting, blockade of HER2 plus use of an aromatase inhibitor in patients with HER2-positive and oestrogen receptor (ER)-positive breast cancer leads to a pathological complete response in 21% of patients. Convergence of HER2 and ER signals on RB1 suggests that a combined pharmacological intervention directed to these targets could be synergistic. To test this approach, we combined palbociclib to block RB1, fulvestrant to block ER, and trastuzumab with pertuzumab to block HER2 in patients with HER2-positive, ER-positive breast cancer.Methods: NA-PHER2 is a multicohort, open-label, exploratory, phase 2 study done at seven sites in Italy. Patients were eligible for the first cohort if they had previously untreated, histologically confirmed, unilateral, invasive, HER2-positive, ER-positive breast cancer and were suitable for neoadjuvant therapy. Patients were treated every 3 weeks with intravenous trastuzumab (8 mg/kg loading dose followed by 6 mg/kg) and intravenous pertuzumab (840 mg loading dose in the first cycle and then at 420 mg) for six cycles plus oral palbociclib (125 mg once a day for 21 days in a 4-week cycle) and intramuscular fulvestrant (500 mg) every 4 weeks for five cycles. The coprimary endpoints were change from baseline in Ki67 expression at 2 weeks of treatment and at surgery (16 weeks after treatment) and changes in apoptosis from baseline to surgery. Secondary endpoints were clinical objective response (according to modified Response Evaluation Criteria in Solid Tumors) and pathological complete response. All patients who met eligibility criteria were assessed for the primary and secondary endpoints. All patients who received at least one cycle of therapy were assessed for safety. This trial is registered with ClinicalTrials.gov, number NCT02530424. The trial is ongoing and two further cohorts are being enrolled.Findings: Between May 20, 2015, and Feb 8, 2016, we enrolled 36 patients, of whom one was deemed ineligible for the study and five were found to be HER2-negative on retrospective analysis. Thus, 35 patients were included in safety analyses and 30 were assessed for the primary and secondary endpoints. At baseline, geometric mean Ki67 expression was 31·9 (SD 15·7), versus 4·3 (15·0) at week 2 (n=25; p<0·0001) and 12·1 (20·0) at time of surgery (n=22; p=0·013). The geometric mean for apoptosis was 1·2 (SD 0·3) at baseline versus 0·4 (0·4; p=0·019) at surgery. A clinical objective response immediately before surgery was achieved by 29 (97%; 95% CI 83-100) of 30 patients. At surgery, eight (27%; 95% CI 12-46) patients had a pathological complete response in breast and axillary nodes. The most frequent grade 3 adverse events were neutropenia (ten [29%]), diarrhoea (five [14%]), and stomatitis, increased alanine aminotransferase, and hypersensitivity reactions (one [3%] of each event). No grade 4 or serious adverse events were recorded in the study and there were no deaths.Interpretation: The combination of palbociclib, fulvestrant, trastuzumab, and pertuzumab had a significant effect on the expression of Ki67 at 2 weeks and at surgery. Triple targeting of ER, HER2, and RB1 in HER2-positive and ER-positive breast cancer could be an effective chemotherapy-free treatment strategy. Further clinical testing and additional molecular characterisation is necessary, not only in hormone receptor-positive tumours but also in tumours without HER2 amplification.Funding: Pfizer and Roche. [ABSTRACT FROM AUTHOR]

Background: In animal models of breast cancer, resistance to continuous use of letrozole can be reversed by withdrawal and reintroduction of letrozole. We therefore hypothesised that extended intermittent use of adjuvant letrozole would improve breast cancer outcome compared with continuous use of letrozole in postmenopausal women., Methods: We did the multicentre, open-label, randomised, parallel, phase 3 SOLE trial in 240 centres (academic, primary, secondary, and tertiary care centres) in 22 countries. We enrolled postmenopausal women of any age with hormone receptor-positive, lymph node-positive, and operable breast cancer for which they had undergone local treatment (surgery with or without radiotherapy) and had completed 4-6 years of adjuvant endocrine therapy. They had to be clinically free of breast cancer at enrolment and without evidence of recurrent disease at any time before randomisation. We randomly assigned women (1:1) to treatment groups of either continuous use of letrozole (2·5 mg/day orally for 5 years) or intermittent use of letrozole (2·5 mg/day orally for 9 months followed by a 3-month break in years 1-4 and then 2·5 mg/day during all 12 months of year 5). Randomisation was done by principal investigators or designee at respective centres through the internet-based system of the International Breast Cancer Study Group, was stratified by type of previous endocrine therapy (aromatase inhibitors only vs selective oestrogen receptor modulators only vs both therapies), and used permuted block sizes of four and institutional balancing. No one was masked to treatment assignment. The primary endpoint was disease-free survival, analysed by the intention-to-treat principle using a stratified log-rank test. All patients in the intention-to-treat population who initiated protocol treatment during their period of trial participation were included in the safety analyses. This study is registered with ClinicalTrials.gov, number NCT00553410, and EudraCT, number 2007-001370-88; and long-term follow-up of patients is ongoing., Findings: Between Dec 5, 2007, and Oct 8, 2012, 4884 women were enrolled and randomised after exclusion of patients at a non-adherent centre, found to have inadequate documentation of informed consent, immediately withdrew consent, or randomly assigned to intervention groups in error. 4851 women comprised the intention-to-treat population that compared extended intermittent letrozole use (n=2425) with continuous letrozole use (n=2426). After a median follow-up of 60 months (IQR 53-72), disease-free survival was 85·8% (95% CI 84·2-87·2) in the intermittent letrozole group compared with 87·5% (86·0-88·8) in the continuous letrozole group (hazard ratio 1·08, 95% CI 0·93-1·26; p=0·31). Adverse events were reported as expected and were similar between the two groups. The most common grade 3-5 adverse events were hypertension (584 [24%] of 2417 in the intermittent letrozole group vs 517 [21%] of 2411 in the continuous letrozole group) and arthralgia (136 [6%] vs 151 [6%]). 54 patients (24 [1%] in the intermittent letrozole group and 30 [1%] in the continuous letrozole group) had grade 3-5 CNS cerebrovascular ischaemia, 16 (nine [<1%] vs seven [<1%]) had grade 3-5 CNS haemorrhage, and 40 (19 [1%] vs 21 [1%]) had grade 3-5 cardiac ischaemia. In total, 23 (<1%) of 4851 patients died while on trial treatment (13 [<1%] of 2417 patients in the intermittent letrozole group vs ten [<1%] of 2411 in the continuous letrozole group)., Interpretation: In postmenopausal women with hormone receptor-positive breast cancer, extended use of intermittent letrozole did not improve disease-free survival compared with continuous use of letrozole. An alternative schedule of extended adjuvant endocrine therapy with letrozole, including intermittent administration, might be feasible and the results of the SOLE trial support the safety of temporary treatment breaks in selected patients who might require them., Funding: Novartis and the International Breast Cancer Study Group., (Copyright © 2018 Elsevier Ltd. All rights reserved.)