Differences in culture and resources between low-income and high-income countries have resulted in unequal rights to health. In the past few decades, developing countries have had an increase in chronic-disease burden, including cancer. Cancer registries are urgently needed in developing countries because the cancer burden is usually poorly known. To fight this burden, the extent of the cancer must be known so that programmes for cancer control can be planned efficiently, not only to implement standards of care but also to define prevention strategies. In this Review, we advocate the need for availability of cancer data and discuss potential opportunities for hospital-based and population-based cancer registries to collaborate in providing these data in low-income countries.