DURING the 11 years 1955 to 1965 just under 6,000,000 people died in England and Wales, 1,084,751 of them, 18-4 per cent, of malignant disease (Registrar General, 1967). The total number of deaths fromtumour in men was 579,527, 19 1 per cent of the total male deaths; while in women the total of tumour deaths was 505,224, 17-6 per cent of the total deaths. This close approximation however gives a false impression as tumour deaths occur predominantly among the older members of the population and there are many more older women than men. A better idea of the relative frequency of neoplasms in men and women may be obtained from a study of the different rates of tumour mortality throughout life. In the six year period 1958 to 1963 the deaths of 234,508 women were attributed to malignantdisease, had the age-specific deathrates for malignant tumours experienced by men applied to women 379,175 deaths would have been expected. It must be remembered, moreover, that the sex organs differ in the two sexes both in anatomical form and physiological function and also in their liabilityto neoplasia. Tumours of the ovary are far commoner than those of the testis, uterine cancer is commoner, especially in younger women than is prostatic cancer which tends to occur most often in much older men. The breast is a large active organ in the female but a rudimentary vestige in the male. Lung cancer on the other hand is very much commoner in males than in females and this difference can reasonably be attributed in large part to the greater frequency of cigarette smoking in men than in women (Kreyberg, 1962). For thesereasons I thought it useful to calculate the relative frequencies of tumours in the two sexes after excluding neoplasms of the lung, the breast and the genital organs. In the same six year period, 1958 to 1963, the number of deaths in this category in women totalled 160,120 while, had the rates seen in men applied to women, the total would have been expected to be 285,352, a female to male ratio of 0-56. A similar calculation was made on the data on the incidence of cancer in four regions of England and Wales for the three vears 1962-64 given in" Cancer Incidence in Five Continents"(Doll, Payne and Waterhouse, 1966). The total cases in women were 42,933; had the male rates applied the total would have been 70,378, a female to male ratio of 0-61.

An equivalent calculation is that which compares the age-adjusted incidence and mortality rates. Dorn and Cutler (1955) gave such rates for the white and non-white elements of the population in 10 Metropolitan areas of the United States. The resident cancer incidence rate per 100,000 was 338-3 for white males and 333-4 for white females, a female to male ratio of 0 99. It was 252-6 for nonwhite males and 293-0 for non-white females, female to male ratio 1-16. After deduction of the rates for cancer of the lung, breast and genital system the rates