Need for epidemiological evidence from the developing world to know the cancer-related risk factors.

The existing evidence on cancer etiology has mostly come from epidemiological studies conducted in the developed world. Now there is an urgent need to gather information on cancer risks in developing countries. Due to recent economic, demographic and health transitions, cancers are on the rise in many developing countries. Future epidemiological studies in these countries should address changing diet, level of physical activity, various environmental and occupational exposures, smoking habits and infections, relative to cancers. In many low resource settings western and conventional lifestyles can be found side by side. Therefore, epidemiological studies in such societies should determine the wide varieties of potentially dangerous exposures, examine changing patterns of related factors and should study other contributing variables as well. Apart from the advantages of such research, there are some challenges. For example, incomplete cancer and death registration, lack of documentation, only partial computerization of medical records, cultural barriers and other technical difficulties can present problems. Some strategies to meet these challenges will be discussed in this paper. There is an immediate need for more detailed epidemiological studies before these developing societies are transformed.