SMALL: Open surgery versus minimally invasive vacuum-assisted excision for small screen-detected breast cancers

TPS614 Background: Mammographic screening programmes reduce breast cancer mortality but detect many small tumours with favourable biology which may not progress. These are treated with surgery and adjuvant therapies, but associated morbidities mean there is a need to reduce overtreatment. Minimally invasive treatments such as vacuum-assisted excision (VAE) have been described but there is no prospective randomised evidence to support their routine use. SMALL (ISRCTN 12240119) is designed to establish the feasibility of using VAE to treat small tumours detected within the UK NHS Breast Screening Programme (BSP). Methods: Phase III multicenter randomized trial comparing surgery with VAE for screen-detected good prognosis cancers. Eligibility criteria are age ≥47 years, unifocal grade 1 tumors (maximum diameter 15mm), strongly ER/PR+ve and HER2-ve, with negative axillary staging. Patients are randomized 2:1 to VAE or surgery, with no axillary surgery in the VAE arm. Excision is assessed radiologically, and if incomplete, patients undergo surgery. Adjuvant radiotherapy and endocrine therapy are mandated in the VAE arm. Coprimary end-points are: (1) Non-inferiority comparison of the requirement for a second procedure. (2) Single-arm analysis of local recurrence (LR) at 5 years after VAE. Recruitment of 800 patients will permit demonstration of 10% non-inferiority of VAE for requirement of a second procedure, ensuring 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%. The DMC 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 optimize recruitment and informed consent. Recruitment challenges are identified by analyzing recruiter/patient interviews, audio-recordings of trial discussions, and by review of screening, eligibility and recruitment data and study documentation. Solutions are developed collaboratively, including recruiter feedback and recruitment tips documents. Results: SMALL opened in December 2019, but recruitment halted for 5 months due to COVID-19. At 11th February 2022, 91 patients had been recruited from 22 centers, with an approached/consented ration of 50%. Drawing from preliminary QRI findings, a recruitment tips document has been circulated (on discussing SMALL, providing balanced information on treatment options and explaining randomization). Individual recruiter feedback has commenced, with wider feedback planned shortly. Conclusion: Despite pandemic-related challenges, SMALL has excellent recruitment to date and is expected to have a global impact on treatment of screen-detected breast cancer. Clinical trial information: 12240119.