Document RjYJ2YwaGxjkjEgoZzXbovJxv

LUNG CANCER IN ASBESTOS MINERS Table 19.--Age Distribution of Adult Males for Table 20.--Annual Death Rates per lOOfiOO for the Province of Quebec, 1951 * Cancer of the Lung in Canada * Ago Group 20-44.................. 45-54............... 55-64.................. +................... Total....... Province Number Percentage 727,135 188,952 128,944 113,467 63 16 11 10 1,158,408 100 Percentage In Cohort 66 19 10 5 100 ' Rapport, 1954, a matter of the same intensity of interest as it is in younger persons. Table 18 also answers a question pre viously raised. It shows that the members of the cohort have not died from lung can cer at an age earlier than the general popu lation, and that such an explanation cannot be offered for the absence of lung cancer in 240 men with more than 40 years of employment referred to on page 643. Before leaving this comparison of the Province with the miners, it should be shown that their age distributions are rea sonably the same. That this is the case can be observed from Table 19. It should be remembered that the miners retire and consequently, it can be expected that the oldest age group will be larger in the general population. The data presented in Table 20 indicate that the lung cancer rate generally decreases after age 70, There fore, we could expect the rate for all people over 65 to be smaller than the rate for the group between 65 and 75, which would apply to the oldest group of miners. It is felt that by using the whole adult male popula tion, we have developed rates for the gen eral population which are somewhat lower than .if we had been able to exclude the people in the genera! population over 75. A comparison between the asbestos miners and the population of the Dominion as a whole was made, using statistical material from several sources. In one source, Phil lips 18 gave age- and sex-specific rates for Canada for three periods between 1931 and 1952. The rates for males are given in Table 20. These figures show strikingly the increase in rates between 1931 and 1952, and this Age Group Under 30 30-34 35-39 40-44 45-49 50-54 SS-S9 GO-64 6S-00 70-74 76-79 80-34 85+ All Ages 1031-1933 0.2 0.9 2.0 3.0 3.2 8.2 12,7 12.3 16.1 IQ.? 15.8 8.2 11.4 IS Groups o( Yean 1941-19(3 0-3 0.9 3*2 5.4 12,5 18.9 27,0 33,7 84.5 30.6 30.0 27.9 IU 7.1 1950-1952 1,0 0.8 3.u 6.5 16-7 *1.1 W.7 71,8 102.9 86,3 83.9 59.7 7t-0 15,8 "Mortality from Lung Cancer In Canada," L931 W 1953. increase is particularly marked after age 50, confirming an observation previously made, to the effect that until recently lung cancer has probably been underdiagnosed in the older age groups in the general popu lation. To use these figures for purposes of comparison, it is necessary to combine the rates for certain age groups in order to conform to the age distributions used in this study. Since the exact populations in each age group for the years indicated is not known, this must be an approximation. However, the rates would be somewhat as follows: Age Group 20-44 45*54 SS*64 65 + Rate 5 27 69 9D-9J These rates are, in general, lower than those developed for the total (proved and suspected) cases of lung cancer among the asbestos miners. The only large difference, however, is in the age group of 65 years and over, and it is quite possible that the rate for this group may have increased for Canada between 1952 and 1954 as it did for the Province of Quebec (Table 17). A further comparison has been made with an over-all rate obtained from the American Cancer Society for respiratory cancer deaths in Canada in 1953, This rate, for males, is 20.8 per 100,000, or 5 more per 100,000 than Phillips' 1950-1952 rate, and compares with 25.3 per 100,000 for proved cases and 33.8 per 100,000 for total cases among the Braun--Truatt 647 SPNY 000306