title: Effect of radiotherapy on survival of women with locally excised ductal carcinoma in situ of the breast: a Surveillance, Epidemiology, and End Results population-based analysis.
abstract: BACKGROUND
  Although it has been previously reported that radiotherapy (RT) effectively reduced the incidence of local recurrence of ductal carcinoma in situ (DCIS) following breast-conserving surgery (BCS), little is known about the effect of RT on survival of patients with locally excised DCIS.
  
  
  METHODS
  Using Surveillance, Epidemiology, and End Results registry data, we selected 56,968 female DCIS patients treated with BCS between 1998 and 2007. Overall survival (OS) and breast cancer-specific survival (BCSS) were compared among patients who received RT or no RT using the Kaplan-Meier methods and Cox proportional hazards regression models.
  
  
  RESULTS
  Median follow-up was 91 months. In the multivariable model, patients receiving postoperative RT had better OS than those undergoing BCS alone (hazard ratio [HR] 0.59, 95% confidence interval [CI] 0.53-0.67, P<0.001). This pattern remained after stratification by estrogen receptor (ER) status and age. In contrast, RT delivery was not significantly associated with improved BCSS (HR 0.71, 95% CI 0.48-1.03, P=0.073). However, after stratifying by the above two variables, RT contributed to better BCSS in ER-negative/borderline patients (HR 0.41, 95% CI 0.19-0.88, P=0.023) and younger patients (≤50 years old; HR 0.37, 95% CI 0.15-0.91, P=0.030).
  
  
  CONCLUSIONS
  Our analysis confirms the beneficial effect of RT on OS in women with locally excised DCIS and reveals the specific protective effect of RT on BCSS in ER-negative/borderline and younger patients.
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Fudan University, Shanghai, People's Republic of China.
authors.forename: Guo-Wei
authors.initials: GW
authors.lastname: Qian
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Fudan University, Shanghai, People's Republic of China.
authors.forename: Xiao-Jian
authors.initials: XJ
authors.lastname: Ni
authors.affiliation: Department of Radiation Oncology, Shanghai Cancer Center and Cancer Institute, Fudan University, Shanghai, People's Republic of China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Fudan University, Shanghai, People's Republic of China.
authors.forename: Yi-Zhou
authors.initials: YZ
authors.lastname: Jiang
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Fudan University, Shanghai, People's Republic of China.
authors.forename: Ke-Da
authors.initials: KD
authors.lastname: Yu
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Fudan University, Shanghai, People's Republic of China.
authors.forename: Zhi-Ming
authors.initials: ZM
authors.lastname: Shao
keywords: breast cancer; breast-conserving surgery; ductal carcinoma in situ; radiotherapy; survival