Document 0vpOEMz1jN15wk2BN57yX4em

200 OCCUPATIONAL TUMORS AND ALLIED DISEASES cancer which he had studied during the preceding 20 years, he found that the average age was from 45 to 50 years, that is, an increase of 10 to 15 years when compared with that noted by Earle in 1823. In the meantime the age for apprenticeship had been increased by law to 16 years (1842). Butlin gave the following age distribution of his 29 cases: Years Cases 25-30 30-35 35-40 40-45 45-50 50-55 55-60 60-65 2 2 2 5 10 4 2 2 Henry, who investigated the age factor in chimney-sweeps' cancer for the period 1911 to 1935, found that the average age at death from this in dustrial neoplasm for the years 1911 to 1915 was 58 years; and for the years 1931 to 1935, 65.8 years (an increase of 7.8 years)} while for the entire period 1911 to 1935, 61.9 years. This figure compares well with the average age of persons dying from scrotal cancer of unknown etiology which was, according to Henry, in 199 cases 57 years. Henry concluded from the evidence available that the remarkable extension of life expectancy of sweeps' cancer can be accounted for to a great extent by the simultaneous shift of the beginning of the exposure period into older age groups and by improved technical, personal and sanitary conditions which were gradually introduced during more recent times. The earlier institution of more successful thera peutic measures during the last five decades contributed doubtlessly to this development. The age distribution of the chimney sweeps' cancers in Henry's series was as follows: Years Cases 30-35 35-40 40-45 4^ J. 0 sss 55-60 60-65 65-70 70-75 75-80 80-85 1 1 5 12 6 14 19 15 13 9 8 Henry mentioned that death from scrotal cancer in sweeps under the age of 35 years is now rare (less than 1 per cent of the total number during the 25 years' period). Whereas Henry considered death from cancer of the scrotum in sweeps under 40 years as rare, Thachrah stated in 1941 that many sweeps die while still young and few live to the age of 50. The data available to Henry did not supply any information concerning the exposure time present in his series. Henry noted, however, that deaths from cutaneous malignancy among sweeps before the age of 45 years was always attributable to a scrotal cancer, whereas from then on also skin cancers of other sites occurred and caused death. The percentage of deaths-'from scrotal cancer in relation to the total death rate from cutaneous malignancy rises, on the other hand, up to the age group 55 to 64 years, but declines