[New options in adjuvant endocrine therapy in breast cancer]. / Nouvelles options en hormonothérapie adjuvante des cancers du sein.

Endocrine therapy is a compulsory step in the adjuvant management of early breast cancer expressing the estrogen receptor, by reducing as much as possible serum and tissue levels of estrogens. Tamoxifen is the standard therapy for non-menopausal women. Ovarian function suppression, in addition to exemestane or tamoxifen, could be an alternative option for young women at high risk of recurrence and non menopausal after adjuvant or neo-adjuvant chemotherapy. Recent studies show a trend for improvement of overall survival and disease-free-survival with aromatase inhibitors among postmenopausal women. However, safety of aromatase inhibitors is controversial and adverse events may lead to switch for tamoxifen with no loss of efficacy. Extension therapy by tamoxifen or aromatase inhibitor after five years of tamoxifen and for a total duration of ten years significantly improves overall survival. There is to date no data supporting the extension therapy after five years of aromatase inhibitor.

Molecular apocrine breast cancers are aggressive estrogen receptor negative tumors overexpressing either HER2 or GCDFP15.

INTRODUCTION: Molecular apocrine (MA) tumors are estrogen receptor (ER) negative breast cancers characterized by androgen receptor (AR) expression. We analyzed a group of 58 transcriptionally defined MA tumors and proposed a new tool to identify these tumors. METHODS: We performed quantitative reverse transcription PCR (qRT-PCR) for ESR1, AR, FOXA1 and AR-related genes, and immunohistochemistry (IHC) for ER, PR, Human Epidermal Growth Factor Receptor 2 (HER2), CK5/6, CK17, EGFR, Ki67, AR, FOXA1 and GCDFP15 and we analyzed clinical features. RESULTS: MA tumors were all characterized by ESR1(-) AR(+) FOXA1(+) and AR-related genes positive mRNA profile. IHC staining on these tumors showed 93% ER(-), only 58% AR(+) and 90% FOXA1(+). 67% and 57% MA tumors were HER2(3+) and GCDFP15(+), respectively. Almost all MA tumors (94%) had the IHC signature HER2(3+) or GCDFP15(+) but none of the 13 control basal-like (BL) tumors did. Clinically, MA tumors were rather aggressive, with poor prognostic factors. CONCLUSION: MA tumors could be better defined by their qRT-PCR-AR profile than by AR IHC. In addition, we found that HER2 or GCDFP15 protein overexpression is a sensitive and specific tool to differentiate MA from BL in the context of ER negative tumors. A composite molecular and IHC signature could, therefore, help to identify MA tumors in daily practice.