Correlation of insulin-like growth factor 1 receptor expression with different molecular subtypes of breast cancer in the UAE

Background: Insulin-like growth factor 1 receptor (IGF1R) activation triggers multiple signaling pathways involved in proliferation and anti-apoptosis in breast cancer (BC). Materials and Methods: Immunohistochemistry for IGF1R was performed on 50 BC cases; expression was assessed for staining intensity and localization pattern (mixed, membranous, and cytoplasmic) which was correlated to hormone receptor status. Results: Of estrogen receptorpositive (ER+) cases, 97.2% were IGF1R+ (48.6% mixed, 43.2% membranous, and 5.4% cytoplasmic pattern) compared to ER- cases (38.5%, 7.7% and 30.8%, respectively) (p=0.003). In progesterone receptor-positive (PR+) cases, 97.2% were IGF1R+, (47.2%, 41.7% and 8.3%, respectively) compared to PR- ones (42.9%, 14.3% and 21.4%, respectively) (p=0.036). For human epidermal growth factor receptor 2-negative (HER2-) cases, 88.8% were IGF1R+ (44.4%, 8.3% and 36.1%, respectively). All HER2+ cases were IGF1R+ (71.4%, 7.1% and 21.4%, respectively) (p=0.015). In conclusion, hormone receptor-positive HER2- cases showed membranous and mixed IGF1R localization. However, hormone receptor-negative and HER2+ showed cytoplasmic or diminished IGF1R expression. Conclusion: These luminal subtypes may benefit from targeted IGFR therapy in the future.