Federal Firefighter Cancer Detection and Prevention Act of 2023 This bill requires the Department of Defense (DOD) to provide its firefighters with medical testing and related services to detect, document, and prevent certain cancers. DOD firefighters may opt out of such testing or services. DOD must document certain information related to the offered testing and services, but must ensure personally identifiable information is removed prior to analyzing the information. DOD may share data with the Centers for Disease Control and Prevention to increase the knowledge and understanding of cancer occurrences among firefighters.