Genetic testing, although a relatively recent tool, has developed into a broad discipline with a number of different applications in cancer ranging from screening individuals for genetic (inherited) predisposition for cancer to predicting tumor behavior. 

There is also a different type of genetic testing based on activity of the genome to uncover critical aspects of tumor cell behaviour, the RNA. The RNA reveals the activity of the genes in the tumor. Since the behavior of the tumor is determined by the activity of its genes, important information regarding tumor behavior can be obtained by analyzing the RNA from a tumor.