Cancer control aims to reduce the incidence, morbidity, and mortality of cancer and to improve the quality of life of cancer patients through the systematic implementation of evidence-based interventions in prevention, early diagnosis, treatment, and palliative care. In the context of a national cancer control program (NCCP), a cancer surveillance program (CSP), built around a population-based cancer registry, is an essential element. Data on the size and evolution of the cancer burden in the population are essential to evaluation of the current situation, to setting objectives for cancer control, and defining priorities. Cancer data are essential in monitoring the progress of the implementation of an NCCP, as well as providing an evaluation of the many individual cancer control activities. In the context of an NCCP, the CSP should provide a focus of epidemiological expertise, not only for providing statistical data on incidence, mortality, stage distribution, treatment patterns, and survival but also for conducting studies into the important causes of cancer in the local situation, and for providing information about the prevalence of exposure to these factors in the population. Cancer surveillance via the population-based registry therefore plays a crucial role in formulating cancer control plans, as well as in monitoring their success.