Cytogenetics is the study of the structure of chromosome material. When cytogenetic testing is used, typically study doctors want to know about changes in the chromosomes seen by microscope with either G-banding (conventional staining of the chromosomes) and/or fluorescent in situ hybridization (FISH). This assists study doctors in identifying chromosomal abnormalities that might affect the development of a particular condition and its treatment. In some forms of cancer, especially hematological malignancies, cytogenetics can determine which chromosomal translocations are present in the malignant cells, facilitating diagnosis and susceptibility to treatment.