ANZ J. Surg. 2005; 75: 260–264 ORIGINAL ARTICLE ORIGINAL ARTICLE SUBSEQUENT SURGERY AFTER INITIAL BREAST CONSERVING SURGERY: A POPULATION BASED STUDY KATRINA SPILSBURY,* JAMES B. SEMMENS,* CHRISTOBEL M. SAUNDERS,† SONJ ˆ A E. HALL* AND C. D. J. HOLMAN* *Western Australian Safety and Quality of Surgical Care Project, Centre for Health Services Research, School of Population Health, University of Western Australia and †QEII School of Surgery and Pathology, QEII Medical Centre, Nedlands, Western Australia, Australia Background: In line with current Australian early breast cancer management guidelines, more women are having breast conserv- ing surgery to treat breast cancer when appropriate. Some women will undergo further surgery because of involved margins, early local relapse, or other factors including patient choice. The aim of this study was to investigate whether socio-economic, demo- graphic or hospital factors were associated with the risk of re-excision or subsequent mastectomy. Methods: A record linkage population-based study on 12 711 women diagnosed with breast cancer in Western Australia from 1982 to 2000 who underwent breast surgery within 12 months of diagnosis was performed. Logistic regression was used to identify social, demographic and hospital factors associated with the risk of undergoing further surgery following initial breast conserving surgery. Results: The proportion of women undergoing initial breast conserving surgery doubled from 33% in 1982–1985 to 72% in 1998–2000. The proportion of women who underwent further surgery following initial breast conserving surgery decreased from 50 to 30% over the same period. The risk of re-excision or subsequent mastectomy was between 2.4 (95% CI 1.7–3.4) and 5.0 (95% CI 3.4–7.4) times greater if initial surgery was performed in a non-metropolitan hospital compared to Perth hospitals. Younger women were between 1.7 (95% CI 1.4–2.0) and 2.1 (95% CI 1.5–3.0) times more likely to undergo re-excisions compared to women aged 50–64 years of age. Conclusions: Young women and women initially treated in non-metropolitan hospitals were at an increased risk of re-excision or a subsequent mastectomy following initial breast conserving surgery to treat breast cancer. Efforts need to be directed towards improv- ing specialist health services outside of Perth if women continue to be treated for breast cancer in non-metropolitan hospitals. Key words: breast cancer, breast conserving surgery, health services research, medical record linkage, Western Australia. Abbreviations: ABS, Australian Bureau of Statistics; ICD, International Classification of Diseases. INTRODUCTION Breast cancer management has seen significant changes in practice over the last 20 years. Results from large clinical trials published since the mid 1980s demonstrated that survival out- comes from breast conserving surgery and radiotherapy were comparable to those after a mastectomy. 1–3 Improved cytotoxic, hormonal and radiation therapy management, and multidisciplinary management practices have also contributed to longer disease- free survival for women diagnosed with breast cancer. 4 Current Australian guidelines reflect these changes and for the manage- ment of early breast cancer recommend women are offered a choice of either breast conserving surgery followed by radio- therapy or a mastectomy where appropriate. 5 In line with these guidelines, there has been a large increase in the proportion of women undergoing initial breast conserving surgery in Australia. In 1993, it was estimated that 34% of Western Australian women underwent breast conserving sur- gery, 6 which by 2000 had increased to 70%. 7 Women from rural areas, older women, women without private health insurance and women of lower socio-economic status were found to undergo less initial breast conserving surgery than other women. 7 However, a certain proportion of women who have initial breast conserving surgery will need to undergo further surgery within a relatively short time. This may be the result of positive or close margins at first excision, disease less amenable to breast conserv- ing surgery than originally expected, early local recurrence or patient choice. The need for re-excision has also been associated with a younger age and the diagnostic method used. 8 The aim of this population-based study was to investigate the total surgical experience during the first 12 months from date of diagnosis for all Western Australian women diagnosed with inva- sive breast cancer from 1982 to 2000. We hypothesized that socio-economic and demographic factors associated with reduced use of initial breast conserving surgery would be less important when considering the risk of re-excision or subsequent mastec- tomy. The Western Australian Health Services Research Data Linkage System (WA Data Linkage System) was used to access cancer registry, death registry and hospital separation data based on the state population of over 1.9 million people spanning an 18-year period. 9 K. Spilsbury BSc, PhD; J. B. Semmens MSc, PhD; C. M. Saunders FRCS, FRACS; S. E. Hall BA, MPH; C. D. J. Holman MB BS, PhD. Correspondence: Katrina Spilsbury, School of Population Health M431, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia. Email: skatrina@dph.uwa.edu.au Accepted for publication 23 October 2004.