The aim of this study is to provide an expression profile of ErbB/HER ligands in breast cancer. We analysed the relationships with their receptors, the bio-pathological features and prognosis.

Epidermal growth factor (EGF), transforming growth factor-α (TGFα), amphiregulin (AREG), betacellulin (BTC), heparin-binding EGF-like growth factor (HB-EGF), epiregulin (EREG) and neuregulins1–4 (NRG1–4) were quantified in 363 tumours by real-time reverse transcription–polymerase chain reaction using TaqMan probes.

Ligands were detected in 80%–96% of the cases, except NRG3 (42%) and EREG (45.5%). At least one ligand was expressed in 304 cases (cut-off: upper quartile). Almost all combinations of receptor and ligand co-expressions were observed, but TGFα is preferentially expressed in tumours co-expressing EGFR/HER3, NRG3 in those co-expressing EGFR/HER4, AREG and EREG in those co-expressing HER2/HER4. EGF and AREG were associated with estradiol receptors, small tumour size, low histoprognostic grading, high HER4 levels. TGFα, HB-EGF and NRG2 were negatively related to these parameters. In Cox univariate analyses, EGF was a prognostic factor.

Our study demonstrates that (i) ErbB/HER ligands, including BTC and EREG, are expressed in most breast cancers; and (ii) TGFα, HB-EGF and NRG2 high expressions are related to the biological aggressiveness of the tumours.