Insulin-like growth factor I (CA) repeats are associated with higher melanoma's Breslow index but not associated with the presence of the melanoma. A pilot study

BACKGROUND: IGF-I-(CA) repeats have been previously analysed in few types of cancer and the results, although discordant in different studies, showed possible associations between cancer and IGF-I(CA)(19) repeats. Aim of this pilot study was to detect a possible association between some of the IGF-I(CA) repeats and the presence of malignant melanoma and its Breslow index. METHODS: Two hundred patients affected with cutaneous malignant melanoma and 100 control healthy subjects were analysed for IGF-I(CA) repeats by fragment analysis sequencing and, partially, confirmed by direct sequencing. RESULTS: A significant association of IGF-I(CA)(19) repeats was observed with melanoma higher Breslow indices (P<0.001), while no association between melanoma patients and the different genotypes of IGF-I(CA) was found. The above mentioned association was confirmed after Bonferroni's correction for multiple comparisons and also by logistic regression analysis adjusted for age, sex and BMI variables. A slight, significant difference (P=0.03) was observed for serum IGF-I values in IGF-I(CA)(19)-positive or IGF-I(CA)(19)-negative subjects. DISCUSSION: The association observed for IGF-I(CA)(19) and malignant melanoma is in keeping with similar results obtained in prostate or breast cancers, suggesting that this type of repeat may be directly or indirectly important in controlling cancer induction and its severity.