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111
1911
" an analysis was made on October 24th, 1910. The date shows that heredity
" plays a part in the development of cancer of the breast in mice. At all age
" periods the disease is more frequent when the mother or either grandmother,
" or all three, had died from cancer of this organ. Without wishing to
" minimise unduly the important influence which heredity is thus demonstrated
" to have, it is necessary to warn against needless alarm, or the awakening of
" pessimistic anticipation of the outlook on future efforts to cope with cancer.
" While it is at present impossible to explain how the liability is transmitted, it
" can be averred with certainty that it does not consist in the inheiitance ot a
" soil more suitable to the growth of cancer in general. It is not inheritance
" of a general constitutional predisposition suitable for growth, as is shown by
" the fact that implantation of cancer is not more successful in mice of a
" cancerous stock than in others. It can only be inferred, with some probability,
" that it is a local or ciicumscribed tissue predisposition, in virtue of which the
" mammary tissue is prone to pass from mere proliferative action into continuous
" or cancerous proliferation. Further, heredity predisposition is only one of
" the factors in play, for it has been found that chronic inflammatory changes
" are remarkably frequent in the mammae of female mice of the laboratory.
" Other factors still unrecognised may exist."
Ages at Death.—The ages at death, which are fully set out in the
tabulated statement given below, which shows that up to thirty-five years of
age the number of deaths from cancer are insignificant, but that above that
period of life they are very serious, because on the average of the ten years
1901-10, it is found that only 16 deaths occurred in the younger period of life,
as contrasted with 325 in older; or translated into percentages only 4-7 per
cent, of the deaths occurred among persons under 35, as against 95*3 per cent,
among those over that age.
Average.
Ages. 1901. 1902. 1903. 1904, 1905. 1906 1907. 1908 1909. 1910. 1901-1910. 1911.
0-5 — 3 4 1 2 1 1 1 — 2 1 1
5-15 1 3 3 2 1 3 3 2 3 1 2 3
15-25 2 5 7 5 3 3 3 8 3 5 4 4
25-35 8 8 5 10 11 7 6 6 10 6 9 5
35-45 33 29 43 43 22 35 39 41 27 40 35 32
45-55 63 75 75 61 74 90 64 63 79 72 71 67
55-65 76 103 95 84 95 110 95 112 96 100 97 92
65-75 75 7° 83 9° 92 74 102 93 94 85 86 87
75-85 27 27 34 22 25 38 27 39 34 47 32 31
85& up wards 4 3 1 5 3 2 8 2 7 3 4 7
289 326 350 323 328 363 348 367 353 361 341 329