doi:10.1016/j.ijrobp.2006.12.043 CLINICAL INVESTIGATION Breast CLINICAL OUTCOME OF BREAST CONSERVATION THERAPY FOR BREAST CANCER IN HONG KONG: PROGNOSTIC IMPACT OF IPSILATERAL BREAST TUMOR RECURRENCE AND 2005 ST. GALLEN RISK CATEGORIES TSZ-KOK YAU, F.R.C.R.,* INDA S. SOONG, F.R.C.R.,* K. CHAN, F.R.C.R.,* M. CHAN, F.R.C.S., † P. CHEUNG, F.R.C.S., ‡ H. W. LAU, F.R.C.S., § AMY T. Y. CHANG, M.B.B.S.,* AND ANNE W. M. LEE, F.R.C.R.* *Department of Clinical Oncology, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China; † Breast Center, Department of Surgery, Kwong Wah Hospital, Hong Kong, China; ‡ Breast Care Center, Hong Kong Sanatorium and Hospital, Hong Kong, China; and § Department of Surgery, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China Purpose: The aim of this study was to evaluate the clinical outcome of breast conservation therapy (BCT) for invasive breast cancers in our predominantly Chinese population. Methods and Materials: Clinical outcomes of 412 T1–2 invasive breast cancers treated by wide local excision and external radiotherapy from 1994 to 2003 were retrospectively analyzed. Only 7% lesions were first detected by mammograms. Adjuvant tamoxifen and chemotherapy were added in 74% and 45% patients, respectively. Results: The median follow-up was 5.4 years. The 5-year actuarial ipsilateral breast tumor recurrence (IBTR) rate, distant failure-free survival, cause-specific survival, and overall survival were 4%, 92%, 96%, and 98%, respectively. The 5-year distant failure-free survival for the low-risk, intermediate-risk, and high-risk categories (2005 St. Gallen) were 98%, 91%, and 80%, respectively (p  0.0003). Cosmetic results were good to excellent in more than 90% of the assessable patients. Grade 3 histology (hazard ratio [HR], 4.461; 95% CI, 1.216 –16.360; p  0.024), age (HR, 0.915; 95% CI, 0.846 – 0.990; p  0.027), and close/positive final margins (HR, 3.499; 95% CI, 1.141–10.729; p  0.028) were significant independent risk factors for IBTR. Both St. Gallen risk categories (p  0.003) and IBTR (HR, 5.885; 95% CI, 2.494 –13.889; p < 0.0005) were independent prognostic factors for distant failure-free survival. Conclusions: Despite the low percentage of mammographically detected lesions, the overall clinical outcome of BCT for invasive breast cancers in the Chinese population is comparable to the Western series. The 2005 St. Gallen risk category is a promising clinical tool, but further validation by large studies is warranted. © 2007 Elsevier Inc. Breast cancer, Chinese, Conservation, Radiotherapy. INTRODUCTION In the female population of Hong Kong, breast cancer is the most common cancer and the third most common cause of cancer deaths (2003 Hong Kong Cancer Registry). Al- though our cumulative lifetime risk (1 in 23) is still much lower than most Western countries, the age-standardized incidence rate has steadily increased from 30.9 to 45.4 per 100,000 standard population throughout the last 2 decades. Similar to many other Asian countries, breast conservation therapy (BCT) was uncommon here until the late 1990s (1, 2). Reasons include the relatively small breast size of Chi- nese women (3), limited radiotherapy facilities, and uncer- tainty about the long-term clinical and cosmetic outcome in our ethnic group. With the increasing recognition of prognostic factors other than those included in the conventional staging, the interpretation of clinical outcome after BCT and compari- son with other series become more complicated. Integrating prognostic factors like age, histologic grade, size of primary tumor, number of positive nodes, HER2 status, and peritu- moral vascular invasion, the risk categories proposed in 2005 St. Gallen meeting (4) may provide a clinically useful Reprint requests to: Tsz-Kok Yau, F.R.C.R., Department of Clin- ical Oncology, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan, Hong Kong, China. Tel: (+852) 25-95-4174; Fax: (+852) 29-04-5216; E-mail: tkokyau@gmail.com Part of the material was presented as a poster at the 48th Annual Meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO), November 5–9, 2006, Philadelphia, PA. Acknowledgments—This study is supported in part by grants from the Hong Kong Cancer Fund. Conflict of interest: none. Received Sept 27, 2006, and in revised form Dec 20, 2006. Accepted for publication Dec 20, 2006. Int. J. Radiation Oncology Biol. Phys., Vol. 68, No. 3, pp. 667– 672, 2007 Copyright © 2007 Elsevier Inc. Printed in the USA. All rights reserved 0360-3016/07/$–see front matter 667