Pregnancy and hCG treatments are considered essential for inhibiting breast cancer. The effect of hCG is accompanied by the synthesis of inhibin, a transforming growth factor involved in cell differentiation and proliferation. Inhibin is considered a tumor suppressor, but its role in the breast is unclear. The aim of this study was to determine the frequency and tissue distribution of the expressions of inhibin-α and β-hCG in breast cancer, and their prognostic relevance with other biological parameters.

334 of formalin-fixed, paraffin embedded tissue blocks were selected, and then immunostained for inhibin-α and β-hCG. The inhibin-α expression was compared with those of β-hCG, ER, PR and HER-2/neu, as well as the tumor characteristics and recurrences.

Inhibin-α and β-hCG were expressed in 87 (26.0%) and 44 cases (13.2%), respectively. Inhibin-α was found in 25.1% of infiltrating ductal carcinomas (67/267), 26.7% of intraductal carcinomas (8/30), 33.3% of lobular tumors (3/9), 80.0% of apocrine carcinomas (4/5) and 21.7% of the other types (5/23). Inhibin-α was correlated with β-hCG (p<0.0001), PR (p=0.010) and HER-2/neu (p=0.021). HCG was focally expressed in the cytoplasm of the conventional types, but the apocrine type displayed diffusely intense cytoplasmic staining, which correlated with histological tumor types (p<0.001).

Inhibin was significantly correlated with the expressions of hCG, PR and HER-2/neu. Therefore, it might be a useful marker in the prevention and hormonal treatment of breast cancer, such as hCG and progesterone. HCG was expressed significantly higher in the apocrine type than the conventional types, suggesting it can be a useful adjunct in differentiating other cancer types.