Original Study Disparities in Surgical Treatment of Early-Stage Breast Cancer Among Female Residents of Texas: The Role of Racial Residential Segregation Chinedum O. Ojinnaka, 1 Wen Luo, 2 Marcia G. Ory, 3 Darcy McMaughan, 1 Jane N. Bolin 1 Abstract In this study of female residents of Texas diagnosed with in situ or localized breast cancer between 1995 and 2012, increasing racial residential segregation was associated with a decreased likelihood of being treated with mastectomy or breast-conserving surgery plus radiotherapy. Racial residential segregation also moder- ated racial disparities in surgical treatment. Introduction: Early-stage breast cancer can be surgically treated by using mastectomy or breast-conserving surgery and adjuvant radiotherapy, also known as breast-conserving therapy (BCT). Little is known about the association between racial residential segregation, year of diagnosis, and surgical treatment of early-stage breast cancer, and whether racial residential segregation influences the association between other demographic characteristics and disparities in surgical treatment. Methods: This was a retrospective study using data from the Texas Cancer Registry composed of individuals diagnosed with breast cancer between 1995 and 2012. The dependent variable was treat- ment using mastectomy or BCT (M/BCT) and the independent variables of interest (IVs) were racial residential segregation and year of diagnosis. The covariates were race, residence, ethnicity, tumor grade, census tract (CT) poverty level, age at diagnosis, stage at diagnosis, and year of diagnosis. Bivariate and multivariable multilevel logistic regression models were estimated. The final sample size was 69,824 individuals nested within 4335 CTs. Results: Adjusting for the IVs and all covariates, there were significantly decreased odds of treatment using M/BCT, as racial residential segregation increased from 0 to 1 (odds ratio [OR] 0.47; 95% confidence interval [CI], 0.41-0.54). There was also an increased likelihood of treatment using M/BCT with increasing year of diagnosis (OR 1.14; 95% CI, 1.13-1.16). A positive interaction effect between racial residential segregation and race was observed (OR 0.56; 95% CI, 0.36- 0.88). Conclusion: Residents of areas with high indices of racial residential segregation were less likely to be treated with M/BCT. Racial disparities in treatment using M/BCT increased with increasing racial residential segregation. Clinical Breast Cancer, Vol. -, No. -, --- ª 2016 Elsevier Inc. All rights reserved. Keywords: Breast cancer, Breast conserving treatment, Disparities, Racial residential segregation, Surgical treatment Introduction Breast cancer is the most common type of cancer and the second leading cause of cancer deaths among women in the United States; 40,450 breast cancererelated deaths are projected to occur in year 2016. 1 Early-stage diagnosis of breast cancer increases the chances of survival and, therefore, reduces mortality rates. 2 However, to maintain the survival advantage of early-stage diagnosis, initiation of recommended therapy after diagnosis is crucial. 3 Treatment of breast cancer is dependent on the stage at which the tumor was diagnosed 4 ; surgical treatment using either mastectomy or breast- conserving surgery (BCS) plus radiation therapy, also known as breast-conserving therapy (BCT), is recommended for individuals diagnosed with early, localized, or operable breast cancer. 4 The survival advantage of BCS is diminished if adjuvant radiotherapy is not administered. 2,5-8 Although the advantage of surgical treatment of early-stage breast cancer is well documented, 4,9 demographic disparities in treatment still exist. Community characteristics, such as rural residence or area poverty, have been associated with decreased likelihood of surgical 1 Department of Health Policy and Management, School of Public Health 2 Department of Educational Psychology 3 Department of Health Promotion and Community Health Sciences, School of Public Health, Texas A&M University, College Station, TX Submitted: Jul 18, 2016; Revised: Sep 1, 2016; Accepted: Oct 12, 2016 Address for correspondence: Chinedum O. Ojinnaka, PhD, MBBS, MPH, Post- Doctoral Research Associate, Department of Health Policy and Management, School of Public Health, Texas A&M University, College Station, TX 77843-1266 E-mail contact: Ojinnaka@sph.tamhsc.edu 1526-8209/$ - see frontmatter ª 2016 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.clbc.2016.10.006 Clinical Breast Cancer Month 2016 - 1