Abstract P3-13-05: Multicentre observational study evaluating why mastectomies are advised by UK multi-disciplinary teams
Authors: Singh JK , McEvoy K , Marla S , Wilcox M , Rea D , Hallissey MT , Francis A ,   West Midlands Research Collaborative
Published: March 2017

Background: Marked variation in mastectomy rates exists across the UK. Identification of variation in practice is a key step towards standardisation of service. The rationale for advising mastectomy by multi-disciplinary teams (MDTs) has not been previously explored in the UK. The main aim of this multicentre observational study was to describe current practice in MDT decision-making for patients undergoing mastectomy. A secondary aim was to determine utilisation of neoadjuvant therapies.

Methods: A multicentre, protocol-driven, prospective cohort study, led by trainees of the West Midlands Research Collaborative was performed during July and September 2015. Data was collected securely using Research Electronic Data Capture. Inclusion criteria were: women &gt;18 years undergoing mastectomy for in situ/invasive disease; presenting with symptomatic or screen detected disease; performed as a primary procedure or following failure of breast conserving surgery (BCS); with or without immediate breast reconstruction (IR).

Results: A total of 1776 patients (1823 mastectomies; 47 bilateral procedures) from 68 units were included. Median age was 63 years (range 20-99). In total 481 (26%) IRs were performed; median IR rate was 22% (range 0-67%).

Mastectomy was advised by the MDT in 1402 (77%) cases. Reasons for advising mastectomy are shown in Table 1.

Table 1. MDT rationale for advising mastectomyRationaleNumber of mastectomiesProportion (%)Large tumour to breast size ratio making BCS unsuitable53029.1Multi-centric disease on imaging37220.4Extensive malignant microcalcification1799.8Previous radiotherapy (Breast/Mantle)1638.9Requiring further surgery for positive margins following BCS1588.7Central tumour1136.2Large primary tumour, patient not suitable for neoadjuvant endocrine or chemotherapy treatment1126.1Neoadjuvant therapy failed to downsize tumour to allow BCS884.8Neoadjuvant therapy apparently successful but mastectomy advised anyway794.3Family History-High Risk512.8

In total 153 patients with oestrogen receptor positive (ER+) tumours were offered neoadjuvant endocrine treatment (NET); 131 (86%) received treatment. A total of 293 post-menopausal women with uni-focal, ER+ tumours, &gt;20mm were not offered NET; mastectomy was advised by MDTs in 202 patients and the rationale for advising mastectomy in 173 patients (86%) was large tumour to breast size ratio.

In total 104 patients with Human Epidermal Growth Factor Receptor 2 over-expressing (HER2+) tumours were offered neoadjuvant chemotherapy and trastuzumab (NACT); 89 (86%) received treatment. A total of 88 women &lt;70 years old with HER2+ tumours, &gt;20mm were not offered NACT; mastectomy was advised by MDTs in 75 patients and rationale for advising mastectomy in 45 women (60%) was large tumour to breast size ratio.

Conclusions: Although most mastectomies are advised for large tumour to breast size ratio, there is inconsistency in the utilisation of neoadjuvant therapies with many potentially eligible patients with large tumours not being given the opportunity to be downsized. Application of standardised recommendations for neoadjuvant treatment resulting in increased and appropriate use of neoadjuvant therapies could reduce the number of mastectomies advised by MDTs.

Citation Format: Singh JK, McEvoy K, Marla S, Wilcox M, Rea D, Hallissey MT, Francis A, West Midlands Research Collaborative. Multicentre observational study evaluating why mastectomies are advised by UK multi-disciplinary teams [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-13-05.