Prognostic significance of IGF-1R expression in patients treated with breast-conserving surgery and radiation therapy

Background: Insulin-like growth factor (IGF) receptor is a key receptor in apoptotic protection, cell adhesion, longevity, and transformation into a cancerous cell and can induce malignant changes in the presence of the IGF ligand. Over-expression of IGF-1R has been associated with resistance to radiation. Inhibitors of IGF-1R have been shown to enhance tumor radiation sensitivity and amplify radiation therapy-induced apoptosis. The purpose of this study is to evaluate the prognostic significance of IGF-1R expression in patients with breast cancer treated with breast conserving therapy. Materials and methods: Paraffin specimens from 345 women with early stage breast cancer treated with BCT were constructed into tissue microarrays and stained for IGF-1R, COX-2 and p53. The molecular profiles were correlated with clinical-pathologic factors, overall, local, and distant relapse-free survival. The association between IGF-1R, other co-variables, and outcome was assessed. Results: IGF-1R over-expression was identified in 197 cases (57%). IGF-1R over-expression was found to be correlated with African-American race (p = 0.0233), p53 status (p = 0.0082) and COX-2 expression (p < 0.0001). While IGF-1R over-expression was associated with lower overall survival (p = 0.0224) in node-negative patients, there was no impact of IGF-1R expression on local control. Conclusions: In node-negative patients, patients with high levels of IGF-1R were found to have a significant reduction in overall survival, but no apparent effect on local control. Given the limited published data on IGF-1R in early stage, conservatively treated patients, further studies investigating IGF-1R expression in this cohort are necessary.