1. ¹Department of Breast Surgery, Matsuyama Red Cross Hospital, 1 Bunkyo, Matsuyama 790-8524, Japan
2. ²Department of Surgery, Beppu Medical Center, Beppu, Japan
3. ³Department of Surgery, Matsuyama Red Cross Hospital, Matsuyama, Japan
4. ⁴Department of Pathology, Beppu Medical Center, Beppu, Japan

Correspondence: Dr S Tsutsui, E-mail: tsutsui@lime.ocn.ne.jp

Revised 21 March 2006; Accepted 24 April 2006; Published online 23 May 2006.

Abstract

To evaluate the c-kit expression in breast cancer, 217 invasive ductal carcinomas of the breast were immunohistochemically stained for c-kit protein. The c-kit expression was positive in 59 (27%) of 217 tumours, while the c-kit expression was negative in 158 (73%) of 217 tumours. There was a significant correlation between a negative expression of the c-kit protein and lymph node metastasis (P<0.0001), and the incidence of a negative expression of the c-kit protein increased as the number of the metastatic lymph nodes increased (P=0.0003). The c-kit expression did not significantly correlate with the tumour size, nuclear grade, oestrogen receptor status, MIB-1 counts and p53 protein expression. A univariate analysis indicated the patients with the negative c-kit expression to have a worse disease-free survival (DFS) than those with the positive c-kit expression (P=0.0041), while a multivariate analysis determined lymph node metastases and the MIB-1 counts to be independently significant factors for DFS. In conclusion, a loss of the c-kit expression was found in about three-fourth of invasive ductal carcinoma of the breast and was associated with lymph node metastases. The prognostic implications of the c-kit expression seem to be due to fact that a loss of the c-kit expression is associated with an advanced stage of breast cancer.