Prognostic associations of insulin-like growth factor-1 receptor in primary uveal melanoma

Abstract

Objective To study the association between immunoreactivity for insulin-like growth factor-1 receptor (IGF-1R) in primary ciliary body and choroidal melanoma and metastatic death in a consecutive, population-based data set. Design Retrospective, consecutive, population-based cohort study. Participants A total of 167 patients with choroidal and ciliary body melanoma, enucleated from 1972 to 1981, with long-term survival data. Methods Specimens were immunostained by using the avidin-biotinylated peroxidase complex method and polyclonal antibodies to IGF-1R. The percentage of tumour area that was immunopositive was recorded. Survival was assessed by Cox multivariate regression analysis. Results The tumour area could be reliably measured from 129 (78%) of the 167 choroidal or ciliary body melanomas. More heavy pigmentation ( p = 0.001), larger number of macrophages ( p = 0.003) and higher microvascular density ( p = 0.060) were associated with a higher percentage of tumour area that was immunopositive for IGF-1R, the reverse being true of extrascleral extension ( p = 0.049). No significant association was observed with ciliary body extension, largest basal tumour diameter, cell type, mean diameter of the 10 largest nucleoli, and presence of extravascular matrix loops and networks ( p = 0.61-0.96). The percentage of tumour area that was immunopositive for IGF-1R was not associated with survival. Conclusions In our data set, immunoreactivity for IGF-IR did not independently predict metastasis from primary uveal melanoma. Partial loss of antigenicity can not be ruled out as a confounding factor because no frozen sections were available. Results of previous studies have likewise been variable, suggesting that immunohistochemical determination of IGF-1R from formalin-fixed, paraffin-embedded specimens is not practical as a routine test.