Abstract
Previous observations on the lower mortality for cancer experienced in populations with a higher frequency of G6PD deficiency support biochemical studies on the role of G6PD during cell proliferation. The general agreement among experimental studies prevented a deeper analysis of the sources of what has been called "epidemiological evidence of the protective role of G6PD deficiency against cancer". This review analyses the methods and findings in those papers, stressing their limitations and emphasising that no final conclusions can be drawn from them. Preliminary results of ongoing epidemiological studies of G6PD deficiency and cancer are presented, although they do not prove or disprove the hypothesis that G6PD deficiency protects against cancer.