Impact of molecular cytogenetics on localization and identification of cancer‐related genes in endocrine tumor development

&NA; In cancer cells, chromosomal aberrations have been recognized as criteria for cancer, and specific genetic alterations are used in clinical practice for diagnostic, prognostic, and therapeutic purposes. Chromosomal aberrations include numerical alterations and structural alterations such as translocations, gene amplifications, deletions, and insertions. With the technical advances in molecular genetics and molecular cytogenetics, the literature focusing on multiple chromosomal alterations in different tumors has been expanding. Multicolor fluorescence in situ hybridization technologies, such as spectral karyotyping, have been used in combination with conventional G‐banding to examine chromosomal alterations in metaphases from cultured tumors and established cancer cell lines. However, in many instances metaphases are not available and karyotyping cannot be performed. In these instances, comparative genomic hybridization and array comparative genomic hybridization have been used on fresh‐frozen or paraffin‐embedded samples to determine genomic amplifications and deletions in tumors. In this review, we provide a brief overview of different cytogenetic techniques that are of use in localizing and identifying genes involved in endocrine tumor development.