To determine whether or not there is a real increase in cancer mortality we must compare cancer death rates for the same ages, since cancer is an old age disease. The effect of age distribution is so great that it is safe to say that any considerable increase in the proportion of the population at the older ages, for instance, the emigration of the young men and women, would cause a noticeable increase in the cancer deaths per 100,000 population, while an influx of young men and women would decrease them. Dr. Frederick L. Hoffman, statistician of the Prudential Life Insurance Company, in a paper on “The Menace of Cancer” published in 1913, and in his comprehensive book on “The Mortality from Cancer” published in 1915, has given the statistics available at the time of writing in a very complete form. These statistics were drawn both from the United States and abroad. From these I have selected a few. In the registration of 1900, the cancer death rate per 100,000 population, which will hereafter be spoken of as the cancer death rate or cancer mortality, increased from 63 in 1900 to 79 in 1913, an increase of over 25 per cent. England and Wales for the same period showed an increase from 83 to 105 and most other European states showed a very considerable increase. Going back forty years, the rate in twenty large American cities was 49 for the period 1881–1885; for 1913 it had increased to 89. In twelve European countries the rate was 69 for the period 1896–1900; for the period 1906–1910, it had increased to 81. These were general population statistics without subdivision by ages. There were also available, however, some extensive statistics subdivided by ages. The cancer death rate in the registration states of the United States of 1900 subdivided into ten-year age groups, 25–34, 35–44, etc., for 1901 compared with 1911 shows an increase in the rate for each age group for the later year, such increase being very considerable for ages above 45, which are the significant ages in cancer. Massachusetts, for the two periods 1901–1905 and 1906–1910, with a different distribution into age groups and subdivided by sexes, showed an increase for each adult group and for each sex separately, in the later period the increase again being very considerable for the older groups. While these are but a few of the statistics, they are illustrative of the trend of practically all, and, standing alone, would appear to indicate a great and rapid increase in cancer mortality. We have, however, later and very extensive statistics from two of the great insurance companies which are not in accord with the above.