need to measure risk factors and screening behaviors, especially among medically underserved individuals.

The Review Group defined cancer control research as the conduct of basic and applied research in the behavioral, social, and population sciences that, independently or in combination with biomedical approaches, reduces cancer risk, incidence, morbidity, and mortality. Thus, optimum cancer prevention and control strategies are those that combine biomedical and public health research to address the process of carcinogenesis across the life span, from prevention to screening and treatment.

The surveillance data reviewed earlier in this chapter reveal considerable gaps in the understanding of cancer risk factors among ethnic minority and medically underserved populations. Greater research is needed to illuminate risk factors both within and across population groups. Such research should address the full range of cancer risk factors, as noted above, including cultural factors affecting health attitudes, behaviors, diet, and other factors, as discussed below.

The Role of Genetics

As in the case with many other diseases such as hypertension or diabetes, large disparities in cancer incidence, mortality, and survival rates are sometimes observed between "racial" groups. These differences are sometimes assumed to be due to genetically determined differences between "races." However, it is important to understand the true nature of genetic variability both within and among "racial" groups and how evolutionary and sociocultural forces have shaped human genetic diversity to understand the meaning of the observed differences.

As noted above, assumptions that differences are due to "race" or genetics may not be justified by the evidence. Behavioral factors (e.g., smoking), environmental factors (e.g., chemical and viral exposure), and socioeconomic factors (e.g., availability, affordability, and accessibility of diagnostic, therapeutic and preventive services) are likely to be the major links responsible for a higher (or lower) incidence or prevalence of cancer in ethnic minority and medically underserved populations (or in any population). The distribution of particular genetic polymorphisms in a population may be a significant factor, however, and must also be considered in comprehensive evaluations of cancer causation. In all comprehensive population-based research on carcinogenesis, the genetic constitutions of the study subjects must be taken into account.

In a small proportion of patients with cancers of various types, mutations in a single gene can be identified as a predominant cause. In such instances, cancers of specific types show a strong tendency to run in families. Examples of genes causing hereditary breast cancer are the BRCA1



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