• immunohistochemistry;
  • lobular carcinoma in situ;
  • oestrogen

Aims:  Oestrogen is a modulator of cell growth and differentiation in the breast. It mediates most of its function through members of the oestrogen receptor (ER) family, ERα and ERβ. Lobular carcinoma in situ (LCIS) is a known risk factor for the development of breast cancer; however, the use of tamoxifen for prevention is based upon data for ER+ (ERα) LCIS associated with invasion, but limited data exist on the use of tamoxifen in cases of ER+ (ERα) LCIS occurring in the absence of invasive carcinoma. The aim of this study was to examine ER expression in LCIS to determine the relationship of ERα to ERβ and, thereby, to determine whether it is of clinical value to measure ERβ along with ERα.

Methods and results:  Core biopsy specimens from 50 patients were examined retrospectively. Histology was reviewed and histological parameters were assessed. Formalin-fixed paraffin-embedded tissue was available for E-cadherin, ERα and ERβ immunohistochemistry. The degree of ERα and ERβ nuclear reactivity was quantified. The patients' mean age was 55 years. The mean follow-up duration was 48 months. All 50 cases of LCIS were E-cadherin-negative. All cases were ERα+ and ERβ+. The staining intensity of ERβ was strong and included staining of periductal stromal cells. The median percentage of cells immunoreactive for ERα was 75% and for ERβ 70% (range 10% weak positive to 100% strong positive). There was a statistically significant relationship between ERβ staining intensity and incidence of ipsilateral breast cancer (P = 0.010).

Conclusions:  The presence and intensity of both stromal and glandular ERβ immunoreactivity suggest that the action of oestrogen on LCIS is on both stromal and glandular cells. Future studies are needed to determine whether the presence of ERβ in LCIS could be targeted to influence the treatment of this disease and perhaps alter its natural history.