Abstract OT1-06-02: SMALL - Open surgery versus minimally invasive vacuum-assisted excision for small screen detected breast cancer: A phase 3 randomised trial

Abstract

Abstract Background:. Mammographic screening programmes have been shown to reduce breast cancer mortality. However, they detect many small tumours with favourable biological features which may not progress during a woman’s lifetime. These are treated with standard surgery and adjuvant therapies, which have associated morbidities. Thus, there is a need to reduce overtreatment of good prognosis tumours found by screening. Minimally invasive treatment approaches have been described but there is no prospective randomised evidence to support their routine use. Vacuum-assisted excision (VAE) is in widespread use for management of benign lesions and lesions of uncertain malignant potential. SMALL (ISRCTN 12240119) is designed to determine the feasibility of using this approach for treatment of small invasive tumours detected within the UK NHS Breast Screening Programme (BSP). Methods:. SMALL is a phase III multicentre randomised trial comparing standard surgery with VAE for screen-detected good prognosis breast cancers. The main eligibility criteria are age ≥47 years, screen-detected unifocal grade 1 tumours with maximum diameter 15mm, which are strongly ER/PR+ve and HER2-ve, with negative clinical/radiological axillary staging. Patients are randomised 2:1 in favour of VAE or surgery; with no axillary surgery in the VAE arm. Completeness of excision is assessed radiologically, and if excision is incomplete, patients undergo open surgery. Adjuvant radiotherapy and endocrine therapy are mandated in the VAE arm but may be omitted following surgery. Co-primary end-points are:1.Non-inferiority comparison of the requirement for a second procedure following excision2.Single arm analysis of local recurrence (LR) at 5 years following VAE. Recruitment of 800 patients over 4 years will permit demonstration of 10% non-inferiority of VAE for requirement of a second procedure. This ensures sufficient patients for single arm analysis of LR rates, where expected LR free survival is 99% at 5 years, with an undesirable survival probability after VAE of 97%. To ensure that the trial as a whole only has 5% alpha, the significance level for each co-primary outcome is set at 2.5% with 90% power. The Data Monitoring Committee will monitor LR events to ensure these do not exceed 3% per year. Secondary outcome measures include time to ipsilateral recurrence, overall survival, complications, quality of life and health economic analysis. A QuinteT Recruitment Intervention (QRI) is integrated throughout SMALL to optimise recruitment and informed consent. Recruitment challenges are identified by analysing recruiter/patient interviews and audio-recordings of trial discussions, and by review of screening, eligibility and recruitment data and study documentation. Solutions to address these are developed collaboratively, including individual/group recruiter feedback and recruitment tips documents. Results:. SMALL opened in December 2019, but recruitment halted in 2020 due to suspension of the NHS BSP for 5 months due to COVID-19. As of 1st July 2021, 55 patients had been approached in 10 centres, with 33 patients randomised (randomisation rate 60%). A further 23 centres are in set-up, with 8 suspended due to the pandemic. Drawing from preliminary QRI findings and insights from patient representatives, a recruitment tips document has been circulated (on introducing and discussing SMALL, providing balanced information. on treatment options and explaining randomisation). individual recruiter feedback has commenced, with wider feedback planned shortly. Conclusion:. Despite pandemic-related challenges, SMALL has an excellent recruitment rate to date and is expected to have a global impact on treatment of breast cancer within mammographic screening programmes. SMALL is funded by the UK NIHR HTA programme, award 17/42/32 Citation Format: Stuart A McIntosh, Charlotte E Coles, Carmel Conefrey, David Dodwell, Kenneth Elder, Jessica Foster, Claire Gaunt, Amanda Kirkham, Iain Lyburn, Jenna Morgan, Sangeetha Paramasivan, Sarah Pinder, Sarah Pirrie, Shelley Potter, Tracy Roberts, Nisha Sharma, Hilary Stobart, Elizabeth Southgate, Sian Taylor-Phillips, Matthew Wallis, Daniel Rea. SMALL - Open surgery versus minimally invasive vacuum-assisted excision for small screen detected breast cancer: A phase 3 randomised trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-06-02.