Predictors of lymph node metastasis in T1 breast carcinoma, stratified by patient age.

It is important to identify T1-substage breast carcinomas (BCs) which are inherently aggressive, so that these can be managed more assertively. The purpose of this study was to distinguish those T1 BCs with the potential to metastasize to axillary lymph nodes from those lacking that ability by multiparametric analysis of several clinicopathologic features. The authors studied 197 patients with invasive BC who had undergone modified radical mastectomy; 161 tumors were ductal and 26 were lobular BCs. The study group was stratified by age into two groups: </=34 years (n = 34) and 35-84 years (n = 153). Pathologic lymph node status was correlated with estrogen receptor (ER) and progesterone receptor (PR) tumor positivity, MIB-1 proliferation index, and immunoreactivity for mutant p53 protein. These factors were studied immunohistologically using standard methodology and microwave-mediated epitope retrieval. Statistical analyses employed accepted techniques. Women in this study ranged from 22 to 84 years of age; 39 (21%) had positive lymph nodes. ER-positive tumors comprised 73% of the total; similarly, 65% were PR positive. The MIB-1 index was greater than 10% in 44% of lesions, and 14% demonstrated labeling for mutant p53 protein. Using crude odds ratio data, the MIB-1 index was the only indicator found to predict lymph node metastasis significantly (p < 0.001). Moreover, even when adjustments were made for patient age, logistic regression analysis confirmed the utility of MIB-1-values of greater than 10% in this context, with a 4.4 greater likelihood of metastasis (p < 0.001). MIB-1 indices of greater than 10% are associated with a risk of lymph node metastasis from T1 BCs, independent of patient age. Hormone receptor status and immunohistologic p53 status are not predictors of nodal involvement in this specific setting.