Research article

Declining recurrence among ductal carcinoma in situ patients treated with breast-conserving surgery in the community setting

Laurel A Habel¹ , Ninah S Achacoso¹ , Reina Haque² , Larissa Nekhlyudov^3,4 , Suzanne W Fletcher³ , Stuart J Schnitt⁵ , Laura C Collins⁵ , Ann M Geiger⁶ , Balaram Puligandla⁷ , Luana Acton¹ and Charles P Quesenberry Jr¹

¹  Division of Research, Kaiser Permanente, Northern California, 2000 Broadway, Oakland, CA 94612, USA

²  Research and Evaluation, Kaiser Permanente, Southern California, 100 South Los Robles, Pasadena, CA 91101, USA

³  Department of Population Medicine, Harvard Medical School/Harvard Pilgrim Health Care Institute, 133 Brookline Avenue, Boston, MA 02215, USA

⁴  Division of Medicine, Harvard Vanguard Medical Associates, 133 Brookline Avenue, Boston, MA 02215, USA

⁵  Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA

⁶  Division of Public Health Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA

⁷  Department of Pathology, Kaiser Permanente Medical Center, 280 West MacArthur Boulevard, Oakland, CA 94611, USA

author email corresponding author email

Breast Cancer Research 2009, 11:R85doi:10.1186/bcr2453

Published:	18 November 2009

Abstract

Introduction

Randomized trials indicate that adjuvant radiotherapy plus tamoxifen decrease the five-year risk of recurrence among ductal carcinoma in situ patients treated with breast-conserving surgery from about 20% to 8%. The aims of this study were to examine the use and impact of these therapies on risk of recurrence among ductal carcinoma in situ patients diagnosed and treated in the community setting.

Methods

We identified 2,995 patients diagnosed with ductal carcinoma in situ between 1990 and 2001 and treated with breast-conserving surgery at three large health plans. Medical charts were reviewed to confirm diagnosis and treatment and to obtain information on subsequent breast cancers. On a subset of patients, slides from the index ductal carcinoma in situ were reviewed for histopathologic features. Cumulative incidence curves were generated and Cox regression was used to examine changes in five-year risk of recurrence across diagnosis years, with and without adjusting for trends in use of adjuvant therapies.

Results

Use of radiotherapy increased from 25.8% in 1990-1991 to 61.3% in 2000-2001; tamoxifen increased from 2.3% to 34.4%. A total of 245 patients had a local recurrence within five years of their index ductal carcinoma in situ. The five-year risk of any local recurrence decreased from 14.3% (95% confidence interval 9.8 to 18.7) for patients diagnosed in 1990-1991 to 7.7% (95% confidence interval 5.5 to 9.9) for patients diagnosed in 1998-1999; invasive recurrence decreased from 7.0% (95% confidence interval 3.8 to 10.3) to 3.1% (95% confidence interval 1.7 to 4.6). In Cox models, the association between diagnosis year and risk of recurrence was modestly attenuated after accounting for use of adjuvant therapy. Between 1990-1991 and 2000-2001, the proportion of patients with tumors with high nuclear grade decreased from 46% to 32% (P = 0.03) and those with involved surgical margins dropped from 15% to 0% (P = 0.03).

Conclusions

The marked increase in the 1990s in the use of adjuvant therapy for ductal carcinoma in situ patients treated with breast-conserving surgery in the community setting only partially explains the 50% decline in risk of recurrence. Changes in pathology factors have likely also contributed to this decline.