Aims: To determine the status of oestrogen receptor (ER) subtypes (ERalpha and ERbeta) in lobular carcinoma in situ (LCIS) of the breast.
Methods and results: Forty-seven cases of LCIS and six cases with normal breast lobules were subjected to immunohistochemistry and evaluated for ERalpha, ERbeta and progesterone receptor (PR) expression. mRNA for ERalpha, ERbeta1 and ERbeta2 were quantified in LCIS and normal lobules using laser microdissection coupled with real-time polymerase chain reaction. LCIS showed a higher level of steroid receptor protein expression than normal lobules. There was no difference in ERbeta1 gene or ERbeta protein expression between normal lobules, pure LCIS, or LCIS associated with invasive breast cancer. No significant difference in expression of either ERalpha or ERbeta was found between pure LCIS and LCIS associated with invasive cancer. However, PR was significantly lower in those cases of LCIS with associated invasive than in those without synchronous invasive disease.
Conclusions: Increased expression of steroid receptors in LCIS suggests their possible role in the biology of LCIS and, for PR, could influence the predisposition of women diagnosed with LCIS to develop invasive breast carcinoma.