1. ¹Academic Surgical Oncology Unit, Division of Surgical Sciences (South), Section of Surgical & Anaesthetic Sciences, The University of Sheffield, Floor K, Royal Hallamshire Hospital, Sheffield S10 2JF, UK
2. ²School of Health and Related Research, Sheffield Health Economics Group, SHARR, University of Sheffield, Regent Court, 30 Regent St, Sheffield S1 4DA, UK
3. ³East Midlands Breast Screening Quality Assurance Reference Centre, Rufford Ward, Nottingham City Hospital NHS Trust, Hucknall Road, Nottingham NG5 1PB, UK

Correspondence: Professor MWR Reed, E-mail: m.w.reed@sheffield.ac.uk

Received 3 September 2004; Accepted 25 October 2004; Published online 21 December 2004.

Abstract

Wide variation in the surgical management of breast cancer exists at hospital, regional, national and international level. To demonstrate whether variation in surgical practice observed at aggregate level between breast units persists following adjustment for case-mix, individual patient-level data from the Trent Breast Screening Programme Quality Assurance database (1997–2003) was analysed. Expected case-mix adjusted mastectomy rates were derived by logistic regression using the variables tumour size, site and grade, patient age and year of presentation, employing the region's overall case-mix adjusted practice as the reference population. The region's 11 breast screening units detected 5109 (3989 invasive) surgically managed primary breast cancers over the 6-year period. A total of 1828 mastectomies (Mx) were performed (Mx rate 35.8%, 95% confidence interval: 34.5–37.1%). Significant variation in mastectomy rates were observed between units (range 25–45%, P<0.0001), and persists following case-mix adjustment (P<0.0001). Two-fold variation in observed to expected unit mastectomy rate coefficient is demonstrated overall (range 0.66–1.36), increasing to almost four-fold variation in cancers less than 15 mm diameter (range 0.55–1.95). Significant variation in surgery for screen-detected primary breast cancer is not explained by case-mix. Further research is required to investigate potential patient and professional causative factors.