Correlation of concurrent lobular neoplasia (LN) and ipsilateral breast cancer recurrence in patients with ductal carcinoma in situ (DCIS) treated with breast-conserving therapy (BCT)

Abstract

585 Background: Multiple clinicopathologic factors have been analyzed for their association with an increased risk of ipsilateral breast tumor recurrence (IBTR) following conservative surgery for DCIS. The incidence of proliferative lesions, such as atypical ductal hyperplasia (ADH), columnar cell changes (CCC), and lobular neoplasia (LN) associated with invasive and non-invasive breast cancer has been reported to be as high as 23%, however, the relevance of these lesions with respect to the natural history of DCIS and the risk of IBTR remains unknown. Methods: 297 patients with DCIS managed with BCT at our institution from 1991 and 1995 were identified from our institutional database. Pathology slides from all cases were retrieved, or prepared from tissue blocks if the original slides were unavailable. Histologic sections from each case were reviewed by a dedicated breast pathologist with particular attention to the presence of LN, ADH, and CCC. Actuarial 5-, 10-, and 15-year local recurrence rates were calculated by the Kaplan-Meier method and compared with the log-rank test. Results: Concurrent LN was present in 43 of 297 patients (15%), ADH in 37 (13%), and CCC in 71 (24%). Median follow-up time was 11.5 years. IBTR occurred in 40 of 225 patients (18%) without LN versus 15 of 43 (35%) with LN (p<0.006; HR 2.35). 5-, 10-, and 15-year cumulative incidence rates of IBTR were twice as high in women with DCIS and LN compared to DCIS alone (Table). Concomitant ADH (HR 1.54) and CCC (HR 1.25) were not significantly associated with IBTR (p=0.20 and p=0.43, respectively). Conclusions: Concurrent LN significantly increases the risk of IBTR in women with DCIS treated with BCT. Further study of risk reducing strategies for women with DCIS associated with LN is necessary. Cumulative Incidences and Hazard Ratios for Ipsilateral Breast Tumor Recurrence by Presence of Concurrent Proliferative Lesion 5-year Cumulative Incidence (CI) 10-year Cumulative Incidence (CI) 15-year Cumulative Incidence (CI) Hazard Ratio ¶ P-value No LN 12% (8;17) 19% (13; 24) 25% (17; 32) 1 LN 25% (11;39) 38% (21; 54) 51% (30; 72) 2.35 < 0.006 No ADH 14% (9;19) 21% (16; 27) 28% (20; 36) 1 ADH 22% (7;36) 25% (10; 41) 41% (21; 61) 1.54 0.20 No CCC 16% (10;21) 21% (15; 28) 27% (19; 35) 1 CCC 15% (6;24) 24% (13; 35) 37% (22; 53) 1.25 0.43 CI - Confidence intervals; ¶ Hazard ratios obtained from the Cox proportional hazards model. All other estimates derived using the Kaplan-Meier method No significant financial relationships to disclose.