Public Health Surveillance is the systematic collection, analysis and interpretation of health related data needed for the planning, implementation and evaluation of public health practice. Public Health Surveillance serves as an early warning system for impending public health emergencies; documents the impact of an intervention, or track progress towards specified goals. 

Cancer Surveillance Systems provide a quantitative portrait of cancer and its determinants in a defined population. The core functions of cancer surveillance are the measurement of cancer incidence (number of new cancers of a specific site/type occurring in a specified population during a year - usually expressed as the number of cancers per 100,000 population at risk), morbidity (refers to having a disease or a symptom of disease, or to the amount of disease within a population) and mortality (another term for death. A mortality rate is the number of deaths due to a disease divided by the total population) for persons with cancer. Cancer Surveillance tells us where we are in the effort to reduce the cancer burden and also generates the observations that form the basis for cancer research and interventions for cancer prevention and control.