CHANGES WITH AGING 



425 



If we admit the possibility that carcinogenesis may be related to 

 the accumulation of tissue injuries, there are two major possibilities. 

 The probability of carcinogenesis may be a continuous function of the 

 cumulative tissue injuries. Or the relationship may be discontinuous, 

 in that the probability of cancer is suddenly and greatly increased 

 when some critical accumulation of damage is reached. In either case, 

 cancer is not an expression of inherent aging but merely of the sum- 

 mation of events imposed from outside the tissue concerned. 



The basic lesion in coronary heart disease is atherosclerosis of the 

 coronary arteries. Figure 2 shows the frequency of finding severe coro- 

 nary atherosclerosis at different ages in consecutive autopsies on men 

 dying from all causes. At average age 35, about 18 per cent of Minne- 

 sota men show a given severe degree of coronary atherosclerosis, and 

 at ages beyond 50 the figure is about 70 per cent. Caucasian men in 

 Hawaii are very similar. So we conclude that by age 50 most of us 

 have very old coronary arteries and it is not surprising if so many of us 

 die from coronary heart disease. 



Japanese men on the Island of Kyushu are very diflPerent indeed 

 (Kimura, 1956; Keys et al., 1958). At 'each age the frequency of this 



80 



70 



1/1 

 ifl 

 O 



J 



u 

 o 



U 50 



I 



H 



< 



u 

 a: 

 u 40 



> 



1/1 



W 30 

 U 



z 



u 



Q 

 U 



10 



30 



— — HAWAII - WHITE 

 MINNESOTA - WHITE 



(D 



HAWAII - JAPANESE 



/ 



<D 



or 



KYUSHU (JAPAN) -JAPANESE 



40 



50 60 



AGE IN YEARS 



70 



80 



Figure 2. Prevalence of severe atherosclerosis of the coronary arteries in men at different 

 ages. Deaths from all causes. 



