Heterogeneous expression of nm23 gene product as a predictor of lymph nodal status in human breast cancer

The nm23 gene was originally identified by differential hybridization of me tastatic murine melanoma cell lines. Some experimental studies demonstrated a significantly low metastatic potential of melanoma cell lines transfecte d with the nm23 gene. In this study, we clarified the relationship between intracellular nm23-immunoreactivity and lymph nodal status of human breast cancer. We analyzed 82 surgically removed breast tumors including 67 invasi ve carcinomas (ductal, lobular and mucinous carcinomas). The nm23 expressio n was diffusely positive in the benign tumors and non-invasive carcinomas. Of the invasive ductal carcinomas, lymph node metastasis was found in 67.7% (21/31) of the focally positive/negative cases and in 18.2% (4/22) of the diffusely positive cases (p<0.001). Immunohistochemically, advanced margins of invasive carcinomas with lymph node metastasis were shown to be negativ e for nm23 expression, while intraductal carcinoma components were positive . This observation suggested that focally positive/ negative nm23 expressio n can be a predictor of lymph node metastasis of invasive ductal breast car cinoma.