Lobular carcinoma in situ as a component of breast cancer: the long-term outcome in patients treated with breast-conservation therapy.

PURPOSE: The purpose of this study is to assess the long-term outcome of breast cancer patients with a component of lobular carcinoma in situ (LCIS) treated with conservative surgery and radiation therapy. METHODS AND MATERIALS: The pathology reports of all patients treated with conservative surgery and radiation therapy at our institution prior to 1992 were reviewed to identify patients who had LCIS as a histologic component. A total of 51 patients were identified. Primary histology of the 51 patients was as follows: 53% infiltrating lobular, 20% invasive and intraductal, 18% invasive ductal, 10% intraductal. There were no patients treated who had LCIS only. One thousand forty-five patients treated conservatively during the same time interval without LCIS served as a control group. All patient characteristics, staging, treatment and outcome variables were entered into a computer database.
RESULTS: As of 3/96, the median follow-up for the LCIS-containing group and control group was 10.6 and 11.4 years, respectively. There were no significant differences in age of presentation, clinical stage, nodal status, estrogen receptor status, or adjuvant therapy received between the two groups. Twenty-two patients (43%) in the LCIS group underwent reexcision. Of those, 69% had residual LCIS in the reexcision specimen. LCIS was characterized as focal in 29%, diffuse in 25%, and not specified in all other cases. The primary histology of the two populations differed significantly with a larger percentage of infiltrating lobular primaries in the LCIS group (53 vs. 5%, p < 0.001). The LCIS group also differed from the control group with respect to the percentage of patients with bilateral disease (17 vs. 8%, p = 0.05), and the percentage of patients with "false negative" mammograms (20 vs. 10%, p = 0.02). There was no statistically significant difference between the LCIS group and control group in the 10-year overall survival (67 vs. 72%), distant disease-free survival (62 vs. 79%), or ipsilateral breast tumor recurrence-free survival (77% LCIS vs. 84% control).
CONCLUSION: Patients with LCIS as a histologic component of breast cancer do not carry a worse prognosis than breast cancer patients without an LCIS component. Furthermore, the comparable local control rates between conservatively treated patients with or without LCIS suggests that patients with a histologic component of LCIS are suitable candidates for conservative surgery and radiation therapy.