Synchronous lobular carcinoma in situ and invasive lobular cancer: Marker or precursor for invasive lobular carcinoma

AimLobular carcinoma in situ (LCIS) is a known risk factor for invasive breast carcinoma, but there is increasing data indicating a possible precursor relationship. This study investigates the incidence of lobular carcinoma in situ that occurs with invasive lobular carcinoma (ILC).MethodsWomen diagnosed with ILC or LCIS from 2000 to 2010 were retrospectively identified and reviewed after institutional review board approval. This group was divided into two cohorts: ILC alone, and LCIS and ILC (ILC/LCIS). Patient demographics, disease characteristics, and treatment modalities were captured. p < 0.05 is considered significant.ResultsA total of 148 patients with ILC or LCIS were identified. Forty-four (54%) patients with only ILC, and 37 (46%) patients with ILC/LCIS were identified. Median age at diagnosis was 62 for ILC and 64 years for ILC/LCIS (p = 0.8). In patients with ILC, total mastectomy was the predominant treatment modality in 28 of 44 (64%) patients, while 18 of 37 (49%) patients with ILC/LCIS underwent breast conservation therapy (p = 0.3). Median largest tumor diameter was 35 mm (range 1–110) for ILC, and 15 mm (range 5–85) for ILC/LCIS (p = 0.03). Nodal status was positive in 17 of 39 (44%) ILC and 13 of 34 (38%) ILC/LCIS (p = 0.6).ConclusionsThe 46% incidence of LCIS associated with ILC in our cohort study is similar to that reported for ductal carcinoma in situ identified with invasive ductal carcinoma at ∼40%. The association of pre-invasive and invasive lobular lesions should be further studied in a large scale prospective study to assess for a precursor relationship.