There is an increased interest in smartphone applications as a tool for delivery of health-care information. There have been no studies which evaluated the availability and content of cancer-related smartphone applications. This study aims to identify and analyze cancer-related applications available on the Apple iTunes platform. The Apple iTunes store was searched for cancer-related smartphone applications on July 29, 2011. The content of the applications was analyzed for cost, type of information, validity, and involvement of health-care agencies. A total of 77 relevant applications were identified. There were 24.6 % apps uploaded by health-care agencies, and 36 % of the apps were aimed at health-care workers. Among the apps, 55.8 % provided scientifically validated data. The difference in scientific validity between the apps aimed at general population versus health-care professionals was statistically significant (P < 0.01). Seventy-nine percent of the apps uploaded by health-care agencies were found to be backed by scientific data. There is lack of cancer-related applications with scientifically backed data. There is a need to improve the accountability and reliability of cancer-related smartphone applications and encourage participation by health-care agencies to ensure patient safety.