Predictors of Local Recurrence in a Population-Based Cohort of Women with Ductal Carcinoma In Situ Treated with Breast Conserving Surgery Alone

Abstract

To identify prognostic indicators of local recurrence (LR) in patients with ductal carcinoma in situ (DCIS) of the breast treated with breast conserving surgery (BCS) alone. A retrospective study was conducted of all women with pure DCIS, diagnosed 1985-1999, referred for tertiary oncologic opinion in British Columbia, treated with BCS without adjuvant radiotherapy. Kaplan-Meier local control (LC) and breast cancer specific survival (BCSS) estimates for the entire group were plotted. Stratified analyses identified subgroups with high Kaplan-Meier 10-year LR. Cox multivariate modeling was used to assess predictors of LR. Kaplan-Meier BCSS rates were compared between two cohorts: those who experienced LR and those who did not have LR. A total of 460 women comprised the study cohort. Median follow-up was 9.4 years. The 15-year LC and BCSS rates were 82% and 97%, respectively. Stratified analyses of LR identified comedo histology, high nuclear grade, tumor size >4 cm or indeterminate size, and positive margins to be associated with significantly higher LR risk, with 10-year LR risks approximating 15-30%. The 10-year BCSS rates for the LR group were 94% compared with 99% for the NoLR group. On Cox regression modeling, high nuclear grade, the presence of comedocarcinoma, and positive margins were significant factors for higher risk of LR. Women with DCIS treated with BCS alone had higher LR risk, and those with a LR were more likely to die of breast cancer. Optimal local treatment is mandatory to minimize the risk of breast cancer death for women with this curable disease.