title: Positive expression of insulin-like growth factor-1 receptor is associated with a positive hormone receptor status and a favorable prognosis in breast cancer.
abstract: OBJECTIVE
  Insulin-like growth factor 1 receptor (IGF-1R) is commonly expressed in primary breast cancers. Understanding the role of IGF-1R signaling in the different subtypes of breast cancer is important because each subtype has a different outcome and requires different treatment modalities. However, the precise biological significance of IGF-1R expression in cancer cells is still unclear. In this study, we examined the expression of IGF-1R in the different molecular subtypes of breast cancer. The effects of IGF-1R expression on the survival rates and outcomes of breast cancer were also examined.
  
  
  METHODS
  IGF-1R expression was evaluated immunohistochemically in tissue microarray blocks constructed from 1,198 invasive breast cancer samples collected from six medical institutions. IGF-1R expression was interpreted according to the human epidermal growth factor receptor 2 (HER2)/neu immunohistochemistry scoring system. Scores of 2+ and 3+ were considered positive.
  
  
  RESULTS
  Positive IGF-1R expression was observed in 65.4% of invasive breast cancer samples. IGF-1R expression was detected in all cancer subtypes (luminal A, 84.4%; luminal B, 75.9%; HER2, 21.2%; triple-negative, 46.6%) and was found to be associated with a positive hormone receptor status and the absence of HER2 amplification (p<0.001). Positive IGF-1R expression was significantly associated with high survival rates (p=0.014). However, a multivariate analysis revealed that the expression levels of IGF-1R did not achieve statistical significance. In the triple-negative cancer subtype, IGF-1R expression was found to be associated with a lower disease-free survival rate (p=0.031).
  
  
  CONCLUSIONS
  Positive IGF-1R expression is associated with a favorable prognosis in breast cancer. IGF-1R is frequently expressed in the luminal A/B subtypes of breast cancer, and its expression is related to the hormone receptor status.
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Su-Jin
authors.initials: SJ
authors.lastname: Shin
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Gyungyub
authors.initials: G
authors.lastname: Gong
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: Department of Pathology, Incheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, Incheon, Korea.
authors.forename: Jun
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Pathology, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: Young Kyung
authors.initials: YK
authors.lastname: Bae
authors.affiliation: Department of Pathology, The Catholic University of Korea College of Medicine, Seoul, Korea.
authors.forename: Ahwon
authors.initials: A
authors.lastname: Lee
authors.affiliation: Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Eun Yoon
authors.initials: EY
authors.lastname: Cho
authors.affiliation: Department of Pathology, Chonnam National University Medical School, Gwangju, Korea.
authors.forename: Ji Shin
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Pathology, Chungnam National University College of Medicine, Daejeon, Korea.
authors.forename: Kwang-Sun
authors.initials: KS
authors.lastname: Suh
authors.affiliation: Department of Pathology, Soonchunhyang University Hospital, Seoul, Korea.
authors.forename: Dong Wha
authors.initials: DW
authors.lastname: Lee
authors.affiliation: Department of Pathology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Woo Hee
authors.initials: WH
authors.lastname: Jung
keywords: Breast neoplasms; Immunohistochemistry; Insulin-like growth factor 1 receptor