Estimation of mutation frequencies in normal mammalian cells and the development of cancer

A current controversy in cancer research is whether the rate of accumulatio n of mutations in normal somatic cells is sufficient to account for the num ber of mutations in malignant cells. This review will focus on the tg;pes o f mutations that can occur in mammalian somatic cells and the frequency at which some of these mutations have been shown to occur in vivo. Human and m ouse mutation detection systems will be highlighted. The possibility that d istinct mutational events can arise from a common precursor will be discuss ed as will the possibility that inherited and sporadic cancers can acquire mutator phenotypes at different times in tumor development. Consideration w ill also be given to a potential relationship between an age-related accumu lation of mutations and cancer.