The relation between anti-TGBFR1 immunohistochemical reaction and low Ki67, small tumor size and high estrogen receptor expression in invasive breast cancer.

Most breast cancers are derived from the luminal epithelium, which composes the inside of the breast ductal structure. Ductal carcinoma in situ (DCIS) leads to invasive ductal carcinoma, but noncancerous intraductal proliferative lesions are also a risk factor for ductal carcinoma. The transforming growth factor beta (TGFB) signaling pathway behaves as a tumor suppressor in the early stage of cancer, and conversely as a tumor growth factor in invasive stages in several cancers. In this study, we performed immunohistochemistry with an antibody that detects the cytoplasmic region of TGFB receptor 1 (TGFBR1) and elucidated TGFBR1 protein expression in luminal epithelial cells of noncancerous breast ducts and in several cases of DCIS and invasive carcinoma. TGFBR1 expression was higher in noncancerous breast tissue than in cancerous tissue, and a difference in expression was also seen among histological subtypes. Comparing the expression level of TGFBR1 in cancer cells and clinico-pathological parameters, cases expressing low TGFBR1 tended to show low estrogen receptor expression, large tumor size (≥10 mm), and a high Ki67 labeling index. These data suggested that TGFBR1 protein expression may be related to the suppression of breast cancer cell growth.