Blurry boundaries: do epithelial borderline lesions of the breast and ductal carcinoma in situ have similar rates of subsequent invasive cancer?

Abstract

Background: The histology of epithelial "borderline lesions" of the breast, which have features in between atypical ductal hyperplasia (ADH) and ductal carcinoma in situ (DCIS), is well described, but the clinical behavior is not. This study reports subsequent ipsilateral breast events (IBE) in patients with borderline lesions compared with those with DCIS.

Methods: Patients undergoing breast-conserving surgery for borderline lesions or DCIS from 1997 to 2010 were identified from a prospective database. IBE was defined as the diagnosis of subsequent ipsilateral DCIS or invasive ductal carcinoma.

Results: A total of 143 borderline-lesion patients and 2,328 DCIS patients were identified. Median follow-up was 2.9 and 4.4 years, respectively. 7 borderline-lesion and 172 DCIS patients experienced an IBE. 5 year IBE rates were 7.7 % for borderline lesions and 7.2 % for DCIS (p = .80). 5 year invasive IBE rates were 6.5 and 2.8 %, respectively (p = .25). Similarly, when analyses were restricted to patients who did not receive radiotherapy, or endocrine therapy, or both, borderline-lesion and DCIS patients did not demonstrate statistically significant differences in rates of IBE or invasive IBE.

Conclusions: When compared with DCIS, borderline lesions do not demonstrate lower rates of IBE or invasive IBE. Despite "borderline" histology, a 5 year IBE rate of 7.7 % and an invasive IBE rate of 6.5 % suggest that the risk of future carcinoma is significant and similar to that of DCIS.

FIG. 1

Kaplan-Meier analyses of ipsilateral breast events for patients with borderline lesions and DCIS for a the entire population, b borderline lesions and DCIS cases not receiving adjuvant radiotherapy, c borderline lesions and low-grade DCIS, and d borderline lesions and low-grade DCIS not receiving adjuvant radiotherapy

FIG. 2

Cumulative incidence analyses of invasive ipsilateral breast events for a the entire population, b borderline lesions and DCIS cases not receiving adjuvant radiotherapy, c borderline lesions and low-grade DCIS, and d borderline lesions and low-grade DCIS not receiving adjuvant radiotherapy

FIG. 3

Kaplan-Meier analyses of ipsilateral breast events for patients with borderline lesions and DCIS that did not receive endocrine therapy for a the entire population, b borderline lesions and DCIS cases not receiving adjuvant radiotherapy, c borderline lesions and low-grade DCIS, and d borderline lesions and low-grade DCIS not receiving adjuvant radiotherapy

FIG. 4

Cumulative incidence analyses of invasive ipsilateral breast events for patients with borderline lesions and DCIS that did not receive endocrine therapy for a the entire population, b borderline lesions and DCIS cases not receiving adjuvant radiotherapy, c borderline lesions and low-grade DCIS, and d borderline lesions and low-grade DCIS not receiving adjuvant radiotherapy