The Pathologic Finding of Combined Lobular Carcinoma in Situ and Invasive Lobular Cancer May Indicate more than Just a High-Risk Marker Role of Lobular Carcinoma in Situ

Abstract

For years, lobular carcinoma in situ (LCIS) has been considered a high-risk marker for developing breast cancer. It is well known that ductal carcinoma in situ is a precursor for the development of invasive ductal carcinoma, and ductal carcinoma in situ is reported to be present in invasive ductal carcinoma in at least 40 per cent of cases. A similar relationship between LCIS and invasive lobular carcinoma (ILC) remains in question. This study evaluates the incidence of synchronous LCIS and ILC at our institution. This is a retrospective review of our tumor registry database of women diagnosed with LCIS or ILC from 2000 to 2014. Pathology reports were evaluated to determine the incidence of pure ILC and mixed ILC/LCIS. Those with both LCIS/ILC (mixed group) and those with pure ILC (pure group) were compared for age, surgical intervention, lymph node involvement, tumor size, nuclear grade, and margins between these two groups. A total of 182 women were identified with LCIS, ILC, or mixed LCIS and ILC. There were76 subjects with pure ILC and 90 with mixed LCIS and ILC. The median and age range for each group were 63.6 (range: 40–97) for the mixed and 64.1 (range: 40–86) for pure groups. Tumor size was evaluated for each group and the median tumor size was 2.5 cm (range: 0.1–7.0cm) for the mixed group and 3.0 cm (range: 0.5–12.5 cm) for the pure group. Nodal involvement was present in 35.23 per cent of the mixed group and 46.3 per cent in the pure group. Surgical treatment for each group was similar, with mastectomy being the preferred surgical option over breast conservation therapy in the mixed and pure groups, 67.07 and 64.71 per cent, respectively. Presently, LCIS is considered a marker, or risk factor, for development of future breast cancer. This retrospective study does identify a strong relationship, 54 per cent, between LCIS and ILC at diagnosis. This high percentage of concurrent LCIS and ILC in surgical/ pathological specimens supports the notion that LCIS may in fact have a precursory role in development of invasive lobular carcinoma of the breast. Additional studies to further investigate this relationship between LCIS and ILC, including genomic analysis, are presently underway.