Prediction of metastasis of primary uveal melanoma by the insulin‐like growth factor‐1 receptor

Abstract

Abstract Purpose To study whether immunoreactivity for the insulin‐like growth factor‐1 receptor (IGF‐IRα) independently predicts metastasis of primary uveal melanoma in a consecutive Finnish data set. Methods Population‐based, retrospective cohort study of 167 choroidal and ciliary body melanomas enucleated from 1972 to 1981 with long‐term survival data. Immunostaining was done by using the avidin‐biotinylated peroxidase complex method, rabbit polyclonal antibodies (N‐20 diluted 1:500) to IGF‐IR and heat pretreatment. Survival was assessed by Cox multivariate regression analysis. Results The tumour area could be reliably measured from 128 (77%) of the 167 consecutive slides which had a choroidal or ciliary body melanoma. The remaining 39 specimens were technically not satisfactory. No significant associations were observed between IGF‐1R immunopositivity and tumor location (P=0.38), largest basal diameter (LBD) (P=0.62), cell type (P=0.84), tumor pigmentation (P=0.59), presence of tumor‐infiltrating macrophages (P=0.33), mean of the ten largest nucleoli (MLN) (P=0.37), presence of extravascular matrix patterns (P=0.67), and microvascular density (MVD) (P=0.39). Adding IGF‐1R did not improve a multivariate model predicting risk of metastasis from primary ciliary body and choroidal melanoma. Conclusion The results suggest that immunoreactivity for IGF‐IRα may not independently predict metastasis of primary uveal melanoma. Because old formalin‐fixed, paraffin‐embedded material was studied, partial loss of antigenicity can not be ruled out as a contributing factor.