The Maryland Department of Health and Mental Hygiene (DHMH) works with local health departments, like the Frederick County Health Department, to investigate concerns about cancer. There is a protocol in which the Maryland Cancer Registry, DHMH Center for Environmental Health Coordination, and the local health department work together to address the concerns. The investigation may involve several stages, depending on the nature of the concern. Some questions can be answered very simply, using publicly available data. In other cases, more investigation with the Maryland Cancer Registry data is required. If the questions still cannot be answered, a more complex investigation may be initiated. Often, the U.S. Environmental Protection Agency, the federal Agency for Toxic Substances and Disease Registry (ATSDR), or the Maryland Department of the Environment may be needed to help with the evaluation of potential environmental exposures.The Maryland Cancer Registry is an ongoing registry since 1992, and the data are used for many different purposes. For example, data are used to look at the numbers and rates of cancer by type of cancer, race, ethnicity, age, gender, and geographic residence. In addition to all of its other responsibilities, the Registry provides data to the counties, which use the data to target cancer surveillance, screening, and prevention activities in conjunction with local health care providers and organizations. The review of state cancer data, to determine whether any particular area has more cancer than would be expected under normal circumstances, is a complicated task that requires additional resources beyond the other activities of the Registry and the health department. However, both the state and county health departments are committed to providing resources to this review of Registry data, because of community concerns.