Abstract 676: Nuclear expression of insulin receptor (InsR) adds prognostic information in primary breast cancer patients with high BMI

Abstract

Abstract Aim and introduction The aim of this study was to elucidate the prognostic importance of nuclear expression of the insulin receptor (nucInsR) in primary breast cancer. The InsR is important for the metabolism, for the insulin-like growth factor (IGF) signaling network and is implicated in breast cancer. Insulin and InsR are interlinked with obesity and body mass index (BMI), which are also associated with breast cancer. The InsR is present both in the membrane and cytoplasm and can additionally translocate to the nucleus. The role of nucInsR is not well understood and the prognostic importance is unclear. Methods The tumor-specific expression of nucInsR was evaluated by immunohistochemistry on invasive breast cancer tissue microarrays from 984 primary breast cancer patients included in a population-based cohort in Sweden. Patients were followed for up to 11 years, the median follow-up for patients still at risk was five years. nucInsR in relation to prognosis was analyzed using Cox regression, adjusted for age, invasive tumor size, axillary lymph node involvement, histological grade, estrogen receptor (ER) status, BMI, tumor storage time, and treatment. Results Status for nucInsR was available for 900 patients (91.5%). nucInsRpos staining was present in 214 patients (23.8%) and was associated with lower age (P=0.004), and lower waist-to-hip ratio (P=0.006), but not with BMI, ER or PR status. During follow-up, 107 patients had a first breast cancer event. nucInsR had no prognostic significant impact among all patients. However, there was a significant effect modification of BMI on nucInsR regarding event-free survival (Pinteraction=0.006). Patients with nucInsRpos-expressing tumors and higher BMI (≥25 kg/m2) had lower risk for any breast cancer event, adjusted HR (0.49; 95% CI 0.26-0.93), while patients with nucInsRpos-expressing tumors and normal BMI (<25 kg/m2) were associated with a non-significant higher risk of events, adjusted HR (1.72; 95% CI 0.93-3.17). Conclusions These results indicate that nucInsR status may add prognostic information in primary breast cancer depending on BMI. Citation Format: Sofie Björner, Ann H. Rosendahl, Maria Simonsson, Andrea Markkula, Karin Jirström, Signe Borgquist, Carsten Rose, Christian Ingvar, Helena Jernström. Nuclear expression of insulin receptor (InsR) adds prognostic information in primary breast cancer patients with high BMI [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 676. doi:10.1158/1538-7445.AM2017-676