Clinicopathological study of chromogranin A, B and BRCA1 expression in node-negative breast carcinoma

Chromogranins are representative proteins contained in endocrine cells of various organs including some ductal cells of the breast. Homology between the BRCA1 protein (1214-1223) and the chromogranins has been detected and suggests that chromogranin may play the role of tumor suppressor like BRCA1. To evaluate whether chromogranins function as tumor suppressors in invasive breast carcinoma, we examined the clinicopathological significance and immunohistochemical expression of chromogranin and BRCA1 in 80 patients with lymph node-negative primary invasive ductal carcinomas. Chromogranin A (CgA) and chromogranin B (CgB) were positive in 21 (26%) and 30 cases (38%) respectively. Expression of CgA was correlated with PR, and lower histological grade (p<0.05 respectively). However, the expression of CgB was not correlated with any immunohistological factor. Expression of both CgA and CgB was not correlated with age, tumor size, and treatment modality. With multivariate analysis, expression of BRCA1 significantly influenced the expression of CgA (p=0.01), while no factor significantly influenced to the expression of CgB. The survival curve of the patients with CgA-negative tumor indicated a tendency to a poorer prognosis than that seen with CgA-positive tumor. The patients with CgB-negative tumors demonstrated a poorer prognosis than seen with patients with CgB-positive tumors (p<0.05). CgA and CgB may mediate tumor progression through some unknown function besides the BRCA1-related function.