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Evidence-based clinical guidelines are essential to maximize patient benefit and to reduce clinical uncertainty and inconsistency in clinical practice. Gaps in the evidence base can be addressed by data acquired in routine practice. At present, there is no international consensus on management of women diagnosed with atypical lesions in breast screening programmes. Here, we describe how routine NHS breast screening data collected by the Sloane atypia project was used to inform a management pathway that maximizes early detection of cancer and minimizes over-investigation of lesions with uncertain malignant potential. A half-day consensus meeting with 11 clinical experts, 1 representative from Independent Cancer Patients' Voice, 6 representatives from NHS England (NHSE) including from Commissioning, and 2 researchers was held to facilitate discussions of findings from an analysis of the Sloane atypia project. Key considerations of the expert group in terms of the management of women with screen detected atypia were: (1) frequency and purpose of follow-up; (2) communication to patients; (3) generalizability of study results; and (4) workforce challenges. The group concurred that the new evidence does not support annual surveillance mammography for women with atypia, irrespective of type of lesion, or woman's age. Continued data collection is paramount to monitor and audit the change in recommendations., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Institute of Radiology.)

Background: Breast reconstruction is offered to improve quality of life for women after mastectomy for breast cancer, but information regarding the long-term patient-reported outcomes of different reconstruction procedures is currently lacking. The Brighter study aimed to evaluate long-term patient-reported outcomes after immediate breast reconstruction (IBR) in a population-based cohort., Methods: Women who underwent mastectomy with IBR for breast cancer in England between 1 January 2008 and 31 March 2009 were identified from National Health Service Hospital Episode Statistics. Surviving women were invited to complete the BREAST-Q, EQ-5D-5L™, and ICECAP-A at least 12 years after the index procedure. Questionnaires were scored according to developers' instructions and compared by IBR type., Results: Some 1236 women underwent IBR; 343 (27.8 per cent) had 2-stage expander/implant, 630 (51.0 per cent) latissimus dorsi, and 263 (21.3 per cent) abdominal flap reconstructions, with a mean(s.d.) follow-up of 13.3(0.5) years. Women who underwent abdominal flap reconstruction reported higher scores in all BREAST-Q domains than those who had other procedures. These differences remained statistically significant and clinically meaningful after adjusting for age, ethnicity, geographical region, socioeconomic status, smoking, BMI, and complications. The greatest difference was seen in scores for satisfaction with breasts; women who had abdominal flap reconstructions reported scores that were 13.17 (95 per cent c.i. 9.48 to 16.87) points; P < 0.001) higher than those among women who had two-stage expander/implant procedures. Women who underwent latissimus dorsi reconstruction reported significantly more pain/discomfort on the EQ-5D-5L™, but no other differences between procedures were seen., Conclusion: Long-term patient-reported outcomes are significantly better following abdominal flap reconstruction than other traditional procedure types. These findings should be shared with women considering IBR to help them make informed decisions about their surgical options., (© The Author(s) 2023. Published by Oxford University Press on behalf of BJS Society Ltd.)

Key Words: Breast cancer, mastectomy, breast conserving surgery, post-mastectomy reconstruction, older women, quality of life., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Published by Elsevier Ltd.)

Purpose: The B-MaP-C study investigated changes to breast cancer care that were necessitated by the COVID-19 pandemic. Here we present a follow-up analysis of those patients commenced on bridging endocrine therapy (BrET), whilst they were awaiting surgery due to reprioritisation of resources., Methods: This multicentre, multinational cohort study recruited 6045 patients from the UK, Spain and Portugal during the peak pandemic period (Feb-July 2020). Patients on BrET were followed up to investigate the duration of, and response to, BrET. This included changes in tumour size to reflect downstaging potential, and changes in cellular proliferation (Ki67), as a marker of prognosis., Results: 1094 patients were prescribed BrET, over a median period of 53 days (IQR 32-81 days). The majority of patients (95.6%) had strong ER expression (Allred score 7-8/8). Very few patients required expedited surgery, due to lack of response (1.2%) or due to lack of tolerance/compliance (0.8%). There were small reductions in median tumour size after 3 months' treatment duration; median of 4 mm [IQR - 20, 4]. In a small subset of patients (n = 47), a drop in cellular proliferation (Ki67) occurred in 26 patients (55%), from high (Ki67 ≥ 10%) to low (< 10%), with at least one month's duration of BrET., Discussion: This study describes real-world usage of pre-operative endocrine therapy as necessitated by the pandemic. BrET was found to be tolerable and safe. The data support short-term (≤ 3 months) usage of pre-operative endocrine therapy. Longer-term use should be investigated in future trials., (© 2023. The Author(s).)

Purpose: Ki67 assessed at diagnosis (Ki67 baseline ) is an important prognostic factor in primary oestrogen receptor-positive (ER +) breast cancer. Proportional change in Ki67 after 2 weeks (∆Ki67 2week ) is associated with clinical benefit from endocrine therapies and residual Ki67 (Ki67 2week ) with recurrence-free survival. The aim was to define the association between Ki67 baseline and after aromatase inhibitor (AI) exposure ∆Ki67 2week and Ki67 2week with key prognostic and biologic factors utilising data from the POETIC study., Patients and Methods: In POETIC 4480 postmenopausal patients with primary ER and/or PgR + breast cancer were randomised 2:1 to 2 weeks' presurgical AI (anastrozole or letrozole) or no presurgical treatment (control). Ki67 was measured centrally in core-cut biopsies taken prior to AI and in core-cuts or the excision biopsy at surgery. Relationships between the Ki67 and biologic factors were explored using linear regression., Results: Established associations of Ki67 baseline with biologic factors including PgR status, tumour grade, tumour size, histological subtype, nodal status, and vascular invasion were confirmed in the HER2- subpopulation. In the HER2 + subpopulation only grade and tumour size were significantly associated with Ki67 baseline . In control group Ki67 2week was 18% lower than Ki67 baseline (p < 0.001) when Ki67 2week was measured in excision biopsies but not when measured in core-cuts. Median suppression by AIs (∆Ki67 2week ) was 79.3% (IQR: -89.9 to -54.6) and 53.7% (IQR: -78.9 to -21.1) for HER2-negative and HER2-positive cases, respectively. Significantly less suppression occurred in PgR- vs PgR + and HER2 + vs HER2- tumours which remained apparent after adjustment for 2-week sample type., Conclusions: The magnitude of this study allowed characterisation of relationships between Ki67 baseline , ∆Ki67 2week and Ki67 2week with high degrees of confidence providing a reference source for other studies. Lower values of Ki67 occur when measured on excision biopsies and could lead to apparent but artefactual decreases in Ki67: this should be considered when either ∆Ki67 2week or Ki67 2week is used in routine clinical practice to aid treatment decisions or in clinical trials assessing new drug therapies., (© 2023. The Author(s).)

Introduction: Shared learning is imperative in the assessment and safe implementation of new healthcare interventions. Magnetic seeds (Magseed®) potentially offer logistical benefit over wire localisation for non-palpable breast lesions but few data exist on outcomes comparing these techniques. A national registration study (iBRA-NET) was conducted to collate device outcomes. In order to share learning, thematic analysis was conducted to ascertain early clinical experiences of Magseed® and wire guided localisation and explore how learning events may be applied to improve clinical outcomes., Methods: A qualitative study of 27 oncoplastic surgeons, radiologists and physicians was conducted in January 2020 to ascertain the feasibility and challenges associated with Magseed® versus wire breast localisation surgery. Four focus groups were asked to discuss experiences, concerns and shared learning outcomes which were tabulated and analysed thematically., Results: Three key themes were identified comparing Magseed® and wire localisation of breast lesions relating to preoperative, intraoperative and postoperative learning outcomes. Percutaneous Magseed® detection, instrument interference and potential seed or wire dislodgement were the most common issues identified. Clinician experience suggested Magseed® index lesion identification was non-inferior to wire placement and improved the patient pathway in terms of scheduling and multi-site insertion., Conclusions: Prospective shared learning suggested Magseed® offered additional non-clinical benefits over wire localisation, improving the efficiency of the patient pathway. Recommendations for improving breast localisation technique, appropriate patient selection and clinical practice through shared learning are discussed that may aid other surgeons in the adoption of this relatively new technique., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Oestrogen receptor positive/ human epidermal growth factor receptor positive (ER+/HER2+) breast cancers (BCs) are less responsive to endocrine therapy than ER+/HER2- tumours. Mechanisms underpinning the differential behaviour of ER+HER2+ tumours are poorly characterised. Our aim was to identify biomarkers of response to 2 weeks' presurgical AI treatment in ER+/HER2+ BCs., Methods: All available ER+/HER2+ BC baseline tumours (n=342) in the POETIC trial were gene expression profiled using BC360™ (NanoString) covering intrinsic subtypes and 46 key biological signatures. Early response to AI was assessed by changes in Ki67 expression and residual Ki67 at 2 weeks (Ki67 2wk ). Time-To-Recurrence (TTR) was estimated using Kaplan-Meier methods and Cox models adjusted for standard clinicopathological variables. New molecular subgroups (MS) were identified using consensus clustering., Findings: HER2-enriched (HER2-E) subtype BCs (44.7% of the total) showed poorer Ki67 response and higher Ki67 2wk (p<0.0001) than non-HER2-E BCs. High expression of ERBB2 expression, homologous recombination deficiency (HRD) and TP53 mutational score were associated with poor response and immune-related signatures with High Ki67 2wk . Five new MS that were associated with differential response to AI were identified. HER2-E had significantly poorer TTR compared to Luminal BCs (HR 2.55, 95% CI 1.14-5.69; p=0.0222). The new MS were independent predictors of TTR, adding significant value beyond intrinsic subtypes., Interpretation: Our results show HER2-E as a standardised biomarker associated with poor response to AI and worse outcome in ER+/HER2+. HRD, TP53 mutational score and immune-tumour tolerance are predictive biomarkers for poor response to AI. Lastly, novel MS identify additional non-HER2-E tumours not responding to AI with an increased risk of relapse., Funding: Cancer Research UK (CRUK/07/015)., Competing Interests: Declaration of interests MB reports grants from Fundacion Alonso Martin Escudero and has a patent filed for the novel molecular subgroups identified in this paper. ELK has a patent filed for the novel molecular subgroups identified in this paper. HT and LK report grants from Cancer Research UK, during the conduct of the study. JMB reports grants from Cancer Research UK, during the conduct of the study; grants and non-financial support from AstraZeneca, Merck Sharp & Dohme, Puma Biotechnology, Clovis Oncology, Pfizer, Janssen-Cilag, Novartis, Eli Lilly, and Roche, outside the submitted work. MD receives consulting fees from AstraZeneca, Lilly, Roche, Radius, H3 Biomedicine and G1. He also receives honoraria from Nanostring. M.C.U.C. has a patent for Breast Cancer Classifier: US Patent No. 9,631,239 with royalties paid and receive research funding from NanoString Technologies and Veracyte advisory role. And has a patent filed for the novel molecular subgroups identified in this paper. All other authors declare no competing interests. The information in this manuscript is subject to a pending patent application., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Objective: To explore the impact of PMRT on PROs of IBBR performed with and without mesh., Summary of Background Data: PMRT is increasingly given to improve breast cancer outcomes but can adversely impact complications after IBBR.Little; however, is known about the impact of PMRT on the PROs of IBBR, especially when mesh is used., Methods: The implant Breast Reconstruction evAluation prospective cohort study recruited consecutive women undergoing immediate IBBR from 81 UK breast and plastic surgical units. Demographic, operative, oncological, and 3-month complication data were collected, and patients consented to receive validated PRO questionnaires at 18-months. The association between IBBR, PMRT, and PROs were investigated using mixed-effects regression models adjusted for clinically-relevant confounders and including a random-effect to account for potential clustering by center., Results: A total of 1163 women consented to receive 18-month questionnaires of whom 730 (63%) completed it. Patients undergoing PMRT (214 patients) reported worse PROs in 3 BREAST-Q domains: satisfaction with breasts [-6.27 points, P = 0.008, 95% confidence interval (CI) (-10.91, -1.63)], satisfaction with outcome [-7.53 points, P = 0.002, CI (-12.20, -2.85)] and physical well-being [-6.55 points, P < 0.001, CI (-9.43, -3.67)]. Overall satisfaction was worse in the PMRT group [OR 0.497, P = 0.002, CI (0.32, 0.77)]. These effects were not ameliorated by mesh use., Conclusions: PMRT may adversely affect PROs after IBBR irrespective of whether mesh is used. These findings should be discussed with all patients considering IBBR and when indications for PMRT are borderline to enable informed decision-making regarding oncological and reconstructive treatment options., Trial Registration: ISRCTN37664281., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To determine (i) the relationship between candidate biomarkers of the antiproliferative (Ki67) response to letrozole and palbociclib alone and combined in ER + /HER2 - breast cancer; and (ii) the pharmacodynamic effect of the agents on the biomarkers., Experimental Design: 307 postmenopausal women with ER + /HER2 - primary breast cancer were randomly assigned to neoadjuvant treatment with letrozole for 14 weeks; letrozole for 2 weeks, then letrozole+palbociclib to 14 weeks; palbociclib for 2 weeks, then letrozole+palbociclib to 14 weeks; or letrozole+palbociclib for 14 weeks. Biopsies were taken at baseline, 2 and 14 weeks and surgery at varying times after stopping palbociclib. Immunohistochemical analyses were conducted for Ki67, c-PARP, ER, PgR, RB1, CCNE1, and CCND1., Results: Higher baselines ER and PgR were significantly associated with a greater chance of complete cell-cycle arrest (CCCA: Ki67 <2.7%) at 14 weeks and higher baseline Ki67, c-PARP, and CCNE1 with a lower chance. The interaction with treatment was significant only for c-PARP. CCND1 levels were decreased c.20% by letrozole at 2 and 14 weeks but showed a tendency to increase with palbociclib. CCNE1 levels fell 82% (median) in tumors showing CCCA but were unchanged in those with no CCCA. Only 2/9 tumors showed CCCA 3-9 days after stopping palbociclib. ESR1 mutations were found in 2/4 tumors for which surgery took place ≥6 months after starting treatment., Conclusions: High CCNE1 levels were confirmed as a biomarker of resistance to letrozole+palbociclib. Ki67 recovery within 3-9 days of discontinuing palbociclib indicates incomplete suppression of proliferation during the "off" week of its schedule., (©2021 The Authors; Published by the American Association for Cancer Research.)

Purpose: Changes occur in the expression of oestrogen-regulated and proliferation-associated genes in oestrogen receptor (ER)-positive breast tumours during the menstrual cycle. We investigated if Oncotype® DX recurrence score (RS), Prosigna® (ROR) and EndoPredict® (EP/EPclin) prognostic tests, which include some of these genes, vary according to the time in the menstrual cycle when they are measured., Methods: Pairs of test scores were derived from 30 ER-positive/human epidermal growth factor receptor-2-negative tumours sampled at two different points of the menstrual cycle. Menstrual cycle windows were prospectively defined as either W1 (days 1-6 and 27-35; low oestrogen and low progesterone) or W2 (days 7-26; high oestrogen and high or low progesterone)., Results: The invasion module score of RS was lower (- 10.9%; p = 0.098), whereas the ER (+ 16.6%; p = 0.046) and proliferation (+ 7.3%; p = 0.13) module scores were higher in W2. PGR expression was significantly increased in W2 (+ 81.4%; p = 0.0029). Despite this, mean scores were not significantly different between W1 and W2 for any of the tests and the two measurements showed high correlation (r = 0.72-0.93). However, variability between the two measurements led to tumours being assigned to different risk categories in the following proportion of cases: RS 22.7%, ROR 27.3%, EP 13.6% and EPclin 13.6%., Conclusion: There are significant changes during the menstrual cycle in the expression of some of the genes and gene module scores comprising the RS, ROR and EP/EPclin scores. These did not affect any of the prognostic scores in a systematic fashion, but there was substantial variability in paired measurements., (© 2021. The Author(s).)

Background: Chemotherapy improves outcomes for high risk early breast cancer (EBC) patients but is infrequently offered to older individuals. This study determined if there are fit older patients with high-risk disease who may benefit from chemotherapy., Methods: A multicentre, prospective, observational study was performed to determine chemotherapy (±trastuzumab) usage and survival and quality-of-life outcomes in EBC patients aged ≥70 years. Propensity score-matching adjusted for variation in baseline age, fitness and tumour stage., Results: Three thousands four hundred sixteen women were recruited from 56 UK centres between 2013 and 2018. Two thousands eight hundred eleven (82%) had surgery. 1520/2811 (54%) had high-risk EBC and 2059/2811 (73%) were fit. Chemotherapy was given to 306/1100 (27.8%) fit patients with high-risk EBC. Unmatched comparison of chemotherapy versus no chemotherapy demonstrated reduced metastatic recurrence risk in high-risk patients(hazard ratio [HR] 0.36 [95% CI 0.19-0.68]) and in 541 age, stage and fitness-matched patients(adjusted HR 0.43 [95% CI 0.20-0.92]) but no benefit to overall survival (OS) or breast cancer-specific survival (BCSS) in either group. Chemotherapy improved survival in women with oestrogen receptor (ER)-negative cancer (OS: HR 0.20 [95% CI 0.08-0.49];BCSS: HR 0.12 [95% CI 0.03-0.44]).Transient negative quality-of-life impacts were observed., Conclusions: Chemotherapy was associated with reduced risk of metastatic recurrence, but survival benefits were only seen in patients with ER-negative cancer. Quality-of-life impacts were significant but transient., Trial Registration: ISRCTN 46099296., (© 2021. The Author(s).)

Purpose: The STAKT study examined short-term exposure (4.5 days) to the oral selective pan-AKT inhibitor capivasertib (AZD5363) to determine if this drug can reach its therapeutic target in sufficient concentration to significantly modulate key biomarkers of the AKT pathway and tumor proliferation., Patients and Methods: STAKT was a two-stage, double-blind, randomized, placebo-controlled, "window-of-opportunity" study in patients with newly diagnosed ER + invasive breast cancer. Stage 1 assessed capivasertib 480 mg b.i.d. (recommended monotherapy dose) and placebo, and stage 2 assessed capivasertib 360 and 240 mg b.i.d. Primary endpoints were changes from baseline in AKT pathway markers pPRAS40, pGSK3β, and proliferation protein Ki67. Pharmacologic and pharmacodynamic properties were analyzed from blood sampling, and tolerability by adverse-event monitoring., Results: After 4.5 days' exposure, capivasertib 480 mg b.i.d. ( n = 17) produced significant decreases from baseline versus placebo ( n = 11) in pGSK3β (H-score absolute change: -55.3, P = 0.006) and pPRAS40 (-83.8, P < 0.0001), and a decrease in Ki67 (absolute change in percentage positive nuclei: -9.6%, P = 0.031). Significant changes also occurred in secondary signaling biomarker pS6 (-42.3, P = 0.004), while pAKT (and nuclear FOXO3a) also increased in accordance with capivasertib's mechanism (pAKT: 81.3, P = 0.005). At doses of 360 mg b.i.d. ( n = 5) and 240 mg b.i.d. ( n = 6), changes in primary and secondary biomarkers were also observed, albeit of smaller magnitude. Biomarker modulation was dose and concentration dependent, and no new safety signals were evident., Conclusions: Capivasertib 480 mg b.i.d. rapidly modulates key biomarkers of the AKT pathway and decreases proliferation marker Ki67, suggesting future potential as an effective therapy in AKT-dependent breast cancers., (©2019 American Association for Cancer Research.)

Introduction: Approximately 55,000 women in the United Kingdom are diagnosed with new breast cancer annually. Since emerging in December 2019, SARS-CoV-2 (coronavirus disease 2019, COVID-19) has become a global pandemic, affecting healthcare delivery worldwide. In response to the pandemic, multiple guidelines were issued to assist with rationalising breast cancer care. The primary aim of the B-MaP-C study is to audit and describe breast cancer management of patients newly diagnosed with breast cancer during the COVID-19 pandemic against pre-COVID-19 management practice in the UK. The implications of changes to management will be determined and the impact of a COVID-19 diagnosis on the patient's breast cancer management will be determined., Methods and Analysis: This is a multi-centre collaborative audit of consecutive breast cancer patients undergoing treatment decisions during the acute and recovery phases of the COVID-19 pandemic. All patients with newly diagnosed primary breast cancer, whose treatment was decided in a multidisciplinary meeting from the 16th March 2020, are eligible for inclusion., Ethics and Dissemination: As this is an audit ethical approval is not required. Each participating centre is required to register the study locally and obtain local governance approvals prior to commencement of data collection. Local audit data will be available to individual participating units for governance purposes. The results of the data analysis will be submitted for publication, as well as disseminated via the ABS newsletter and a webinar. All data will be presented at national and international conferences, circumstances permitting., Registration Details: Each participating centre received local governance audit registration., (© 2020 Published by Elsevier Ltd on behalf of Surgical Associates Ltd.)

The major changes in hormone levels that occur through the menstrual cycle have been postulated to affect the expression of hormone-regulated and proliferation-associated genes (PAGs) in premenopausal ER+ breast cancer. Whilst previous studies have demonstrated differences in gene expression, here, we investigated if there are within patient changes in the expression of oestrogen- and progesterone-regulated genes (ERGs and PRGs) and PAGs in ER+ breast cancer during the menstrual cycle. Samples from 96 patients in two independent prospective studies of the effect of menstrual cycle on ER+ breast cancer were used. Plasma hormone measurements were used to assign tumours to one of three pre-defined menstrual cycle windows: W1 (days 27-35 and 1-6; low oestradiol and low progesterone), W2 (days 7-16; high oestradiol and low progesterone) and W3 (days 17-26; intermediate oestradiol and high progesterone). RNA expression of 50 genes, including 27 ERGs, 11 putative PRGs and seven PAGs was measured. The AvERG (geomean of PGR , GREB1 , TFF1 and PDZK1 ) was used as a composite measure of ERG expression and showed significant changes between the three windows of the menstrual cycle increasing over 2.2-fold between W1 and W2 and decreasing between W2 and W3 and between W3 and W1. Proliferation gene expression also varied significantly, following the same pattern of changes as ERG expression, but the changes were of lower magnitude (1.4-fold increase between W1 and W2). Significant changes in the expression of eight individual ERGs, including GREB1 , PGR and TFF1 , and two PAGs were observed between W1 and either W2 or W3 with all genes showing higher levels in W2 or W3 (1.3-2.4-fold; FDR 0.016-0.05). The AvProg, a composite measure of PRG expression, increased significantly (1.5-fold) in W3 compared to W1 or W2 but no significant changes were observed for individual PRGs. In conclusion, we observed significant changes in ERG, PRG and PAG expression in ER+ breast tumours during the menstrual cycle that may affect the assessment and interpretation of prominent biomarkers (e.g. PgR) and commonly used multigene prognostic signatures in premenopausal ER+ breast cancer., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2019.)

To investigate the impact of sampling methodology on gene expression data from primary estrogen receptor-positive (ER+) breast cancer biopsies, global gene expression was measured in core-cut biopsies at baseline and surgery from patients randomly assigned to receive either two weeks of presurgical aromatase inhibitor (AI; n = 157) or no presurgical treatment (n = 56). Those genes most markedly altered in the AI group (eg, FOS , DUSP1 , RGS1 , FOSB ) were similarly altered in the no treatment group; some widely investigated genes that were apparently unaffected in the AI group (eg, MYC ) were counter-altered in the control group, masking actual AI-dependent changes. In the absence of a control group, these artefactual changes would likely lead to the most affected genes being the erroneous focus of research. The findings are likely relevant to all archival collections of ER+ breast cancer.

•Multicentre retrospective study involving breast and plastic units across the UK.•Will produce valuable data regarding management and outcomes.•Will inform decision making and help shape a future definitive study., (© 2017 The Authors.)

Introduction: Wide local excision and adjuvant radiotherapy is the standard of care for early breast cancer. For large tumours, however, mastectomy is frequently recommended as conventional breast-conserving techniques often result in poor cosmetic outcomes. Therapeutic mammaplasty (TM) may extend the boundaries of breast-conserving surgery by combining breast reduction and mastopexy techniques with tumour excision, preserving a natural breast shape and avoiding the need for mastectomy. The prevalence of this operative option among surgeons in the UK and its success rate are unknown. The TeaM study is a multicentre prospective study that aims to investigate the practice and outcomes of TM., Methods and Analysis: Breast centres performing TM will be invited to participate through the research collaborative network and the professional associations. All patients undergoing TM between September 2016 and March 2017 will be included. Demographic, operative, oncological and complication data within 30-days of surgery will be collected. The primary outcome will be unplanned re-operation for complications. Secondary outcomes will include unplanned readmission, re-excision rates and time to adjuvant therapy. Prospective data on 500 patients from 50 centres are anticipated. Exploratory analyses will identify predictors for complications and inform the design of a definitive study., Ethics and Dissemination: Research ethics approval is not required for this study. This has been confirmed by the on-line Health Research Authority decision tool. This study will provide novel information regarding the practice and outcomes of TM in the UK. This will inform decision-making for patients and surgeons and inform future research. Dissemination of the study protocol will be via the Mammary Fold Academic and Research Collaborative, the Reconstructive Surgery Trials Network and the professional associations, the Association of Breast Surgery and British Association of Plastic, Reconstructive and Aesthetic Surgeons. Results will be presented at relevant surgical conferences and published in peer-reviewed journals., (© 2016 The Authors.)