Background and aim of the study:

Several studies have indicated that increased levels of insulin-like growth factor 1 (IGF-I) or altered levels of its binding proteins are associated with an increased risk of the most common cancers, including cancers of the colorectal, lung, breast and prostate. The aim of this study is to investigate the expression of IGF-1 in both calcifying epithelial odontogenic tumor (CEOT) and ameloblastoma.

Materials and methods: The research sample consisted of 23 paraffin blocks from Oral Pathology Department, Faculty of Dentistry, Damascus University, including six biopsies of CEOT, two biopsies of the plexiform ameloblastoma and 14 biopsies of the follicular

ameloblastoma. All specimen were prepared and immunostained with rabbit polyclonal antibody to IGF-1. Immunostaining was assessed according to German-semiquantitative scoring system, and then the results were aggregated and statistically analyzed using SPSS version 13.0 (Student’s test for two independent samples, one-way analysis of variance, Kruskal–Wallis test and Mann–Whitney U-test), the significance level P value less than 0.05 was considered statistically significant.

Results: All CEOT and ameloblastoma samples were positive for IGF-1 staining, except one sample of ameloblastoma, which was negative. The results showed that there were no statistically significant differences between CEOT and ameloblastoma in the values of IGF-1 expression (P=0.993) and IGF-1 expression rates (P= 0.874) and in the frequency of IGF-1 expression (P= 0.761) and IGF-1 staining intensity score (P= 0.731).