AOSOP11 KI67 LEVEL IN HORMONE-RECEPTOR-POSITIVE BREAST CANCER: A RETROSPECTIVE REVIEW OF 8990 KOREAN WOMEN

s, 5th AOS and 9th Annual Conference of OOTR, 2013 / European Journal of Cancer 49S1 (2013) S1−S22 S5 Methods. RNA interference (RNAi) and RNA activation (RNAa) were used to down-regulate and up-regulate the expression of WT1, respectively. The impacts of WT1 on proliferation, cell cycle distribution, apoptosis, invasion, and migration of breast cancer cells were detected by CCK8, annexin V/PI, and Transwell methods, respectively. Results. The mRNA and protein expression of WT1 in MDAMB-321 cells were significantly higher than that in MCF-7, Bcap-37, and SKBR-3 cells. The WT1 small interfering RNA (siRNA) could effectively inhibit the WT1 expression of MDAMB-231 at 48h after transfection. Down-regulation of WT1 decreased cell proliferation, the proportion of cells in S and G2 phase as well as the invasion and migration ability, and increased the proportion of apoptotic cells and cells in G1 phase. WT1 double-stranded RNA (dsRNA) could increase the expression of WT1 in MCF-7 cells, and promoted the proliferation, invasion, and migration of MCF-7 cells. In addition, we also found that the inhibitor of differentiation 1 (Id1), a key molecule in cell proliferation and metastasis in breast cancer, was the target gene of WT1. Finally, we used transforming growth factor b1 (TGF-b1) to induce WT1 expression in MCF-7 cells with the concentration of 10ng/mL for 48h.After treatment,MCF-7 cells appeared fromepitheliallike to mesenchymal-like. Moreover, the expression of WT1 and Id1 in MCF-7 cells was increased, and the ability of invasion and migration were enhanced. Discussion. WT1 plays an oncogenic role in the progression of breast cancer, and promotes the proliferation, invasion, and migration of breast cancer cells partly through regulating Id1. Funding. This study was supported by NSFC (No. 81102030). The authors declared no conflicts of interest. AOSOP11 KI67 LEVEL IN HORMONE-RECEPTOR-POSITIVE BREAST CANCER: A RETROSPECTIVE REVIEW OF 8990 KOREAN WOMEN J. Kima *, W. Hana, Y.H. Parkb, S. Jungc, J. Roc, H. Moona, S. Ahna, J. Leea, M. Kima, D. Noha. aSeoul National University Hospital, Seoul, South Korea, bSamsung Medical Center, Seoul, South Korea, cNational Cancer Center, Seoul, South Korea Introduction. Breast cancer at a young age has poor prognosis and the number of young patients being diagnosed is increasing. Tumour proliferation marker Ki67 is known to be associated with prognosis and response to cancer therapy. This study aimed to determine the relationship between age and Ki67 in hormone-receptor-positive breast cancer. Methods.We retrospectively reviewed 8990 consecutive cases of hormone-receptor-positive invasive breast cancer among Korean women. Multicentre data for Ki67 level identified by immunohistochemistry (IHC) and age at diagnosis were analysed. Patients who had undergone neoadjuvant systemic therapy and who had in-situ carcinomas were excluded. Data were obtained from Seoul National University Hospital (SNUH), Samsung Medical Center (SMC), and National Cancer Center (NCC) after approval of the institutional review board from each institute. Results. Total 6222 cases from SNUH, 976 from SMC, and 1863 from NCC were included. The three datasets were analysed separately due to the variable IHC method in each institute. Mean ages were 49.30 years (range 20−86), 47.75 years (range 22−81), and 45.31 years (range 25−59) in SNUH, SMC, and NCC, respectively, and mean Ki67 levels were 4.66% (range 1– 100), 22.98% (range 1−97), and 14.58% (range 1−90). Ki67 levels were inversely correlated with age at diagnosis in all three datasets. Ki67 levels were significantly higher among patients aged younger than 40 years compared with 40 years and older (mean Ki67 5.97 vs 4.41, p<0.001; 28.60 vs 21.88, p<0.001; and 17.01 vs 14.03, p<0.001, in SNUH, SMC, and NCC, respectively). Mean ages were younger when Ki67 level was dichotomised into <10% versus 10%, <20% versus 20%, and <14% versus 14%, in SNUH, SMC, and NCC (p<0.001, p=0.03, and p<0.001, respectively). Discussion. Ki67 levels were significantly higher in hormonereceptor-positive breast cancer at a young age. This may be associated with the poor prognosis and poor response to endocrine therapy in young patients with this disease. However, due to the variability of assessing Ki67, careful interpretation should be made to achieve validity. Funding. None declared. The authors declared no conflicts of interest. AOSOP12 PRELIMINARY STUDY OF SPECTRAL CT IMAGING IN DIFFERENTIATING PULMONARY SQUAMOUS CELL CARCINOMA AND SMALL CELL CARCINOMA Y. Liua, J. Yub *, W. Looc, L. Chowc, A. Yipc. aThe Affiliated Hospital of Ningxia Medical University, Yinchuan, China, bNingxia People’s Hospital, Yinchuan, China, cOrganisation for Oncology and Translational Research and UNIMED Medical Institute, Hong