Expression of adhesion proteins E-cadherin, alpha-catenin, beta-catenin and gamma-catenin is different in T1 and T2 breast tumours.

Breast cancer is the most common malignancy in women. Although an increasing number of patients with breast cancer are being cured by surgery, a considerable number of patients suffer relapse in the form of metastases after surgery. E-cadherin and catenins have documented roles in breast cancer progression. Mammography is supposed to decrease breast cancer mortality by detecting tumours while they are small and before they have reached a clinically detectable stage. In the present study, we wanted to evaluate whether there are differences in expression patterns of adhesion proteins, shown to be crucial in the metastatic process, between small tumours detected by mammography and clinically detected large tumours. Expression of E-cadherin, alpha-catenin, beta-catenin and gamma-catenin was analysed using immunohistochemistry methods in 86 invasive breast carcinomas detected by mammography and compared with 90 clinically palpable invasive breast carcinomas. In the group of tumours detected by mammography (86 samples), reduced expression of E-cadherin was observed in 12 (14%) samples. Reduced expression of alpha-catenin was observed in four (4.6%) samples, and three (3.5%) samples showed reduced expression of beta-catenin. All samples showed strong expression of gamma-catenin. When expression patterns of these proteins were evaluated in 90 clinically detected tumours, we observed reduced expression of E-cadherin in 58 (64.4%) samples, 12 (13.3%) samples showed reduced expression of alpha-catenin, while nine (10%) samples showed reduced expression of beta-catenin. Strong expression of gamma-catenin was detected in all tumours also in this group.Statistical analyses revealed a highly significant difference in expression of E-cadherin (p<0.001). However, no statistically significant differences were observed in expression of alpha-catenin (p = 0.081) and beta-catenin (p = 0.092) between the two groups of tumours. Results indicate that T1 breast tumours harbour less alterations in E-cadherin-catenin complexes and therefore are probably less likely to disseminate, and patients probably have a better prognosis than if tumours are diagnosed as T2.