Abstract: A gene useful as a prognostic indicator of survival of patients afflicted with cancers such as breast cancer is described. Also disclosed are methods for screening potential therapeutic agents, such as antitumor agents, based on their modulation of the expression of a TRIP13 gene, or splice variants thereof, along with methods for diagnosing cancerous, or potentially cancerous, conditions as a result of the expression, or patterns of expression, of such genes, including changes in copy number. Also disclosed are methods for detecting or determining functionally related genes, where disruption of TRIP13 may affect such related-gene expression, as well as methods for treating cancer based on targeting expression products of such genes and determining genes involved in the cancerous process.