Expression of the insulin-like growth factor-I receptor in primary breast cancer and lymph node metastases:: Correlations with estrogen receptors α and β

Numerous laboratory studies and some epidemiological data have suggested the involvement of the insulin-like growth factor-I receptor (IGF-IR) in breast cancer development and progression. However, data on IGF-IR expression in human tissues, including breast cancer sections, are limited and often inconsistent. We therefore examined by immunohistochemistry the expression of IGF-IR in primary tumors and breast cancer metastases to lymph nodes, and correlated IGF-IR positivity with estrogen receptor (ER) status and selected clinicopathological features. We found that 1) IGF-IR was expressed in primary tumors as well as in lymph node metastases, but the expression in primary tumors was more frequent (56% vs. 44.4%); 2) IGF-IR expression in primary tumors was associated with negative node status (p<0.033); 3) in node-negative primary tumors, IGF-IR positively correlated with ER[3 (p<0.008; r=0.538), but not with ERalpha, tumor size or grade; 4) both IGF-IR-positive and IGF-IR-negative primary tumors were found to produce IGF-IR-positive as well as IGF-IR-negative metastases; 5) in metastases, IGF-IR expression did not associate with ERalpha, ERbeta or any of the studied pathobiological markers. The results suggest that IGF-IR could become a viable pharmaceutical target in breast cancer therapy, but such therapy should be based on IGF-IR assessment in primary tumor and metastasis in each potential patient.