Day 035 - 12 Oct 94 - Page 39
1 "The occurrence of both breast and colon cancer is
2 strongly associated with modern affluence, suggesting that
3 they may share important aetiological factors. Indirect
4 evidence, largely based on differences in cancer rates
5 between countries and changes in rates amongst migrants,
6 has implicated diet as potentially important, but specific
7 aspects of diet have not yet been definitively identified
8 from epidemiological investigations. Much of the
9 available information is derived from case-control studies
10 in which reports from cancer patients about their past
11 dietary practices are compared with those of persons
12 without cancer. The possibility of biased reporting of
13 former diets in these studies is difficult to eliminate.
14 Prospective cohort studies, in which dietary variables
15 measured among a large number of people are related to
16 subsequent risks of cancer, should provide more dependable
17 data, but these are only beginning to be available because
18 it takes time to accumulate enough cancer cases. The
19 existing limited data suggest that, despite gross
20 similarities i n the epidemiology of breast and colon
21 cancer, incidence of the colon cancer is likely to be more
22 responsive to dietary change and thus be easier to
23 prevent".
24
25 I am not sure whether I am right or not, but does that not
26 reflect what I just put to you a moment ago, that
27 Dr. Willett's view in relation to diet and cancer is
28 stronger in the field of colon cancer than it is in
29 relation to breast cancer?
30 A. Allow me a moment to just re-read that sentence, if
31 I may?
32
33 Q. Yes.
34 A. Yes, he does seem to be saying here that dietary
35 changes are more likely to affect the incidence of colon
36 cancer than breast cancer, and I did not understand that
37 to be precisely what you had asked me earlier.
38
39 Q. It was not precisely, but surely this is right, is it not,
40 Dr. Barnard, that if diet has a role in the aetiology of
41 cancer, then the incidence of cancer is likely to be
42 responsive to changes in the diet, is it not?
43 A. There is a very important distinction between
44 responsiveness to treatment and whether or not an
45 aetiologic agent is identified -----
46
47 Q. Sorry, let me interrupt, not treatment -- prevention is
48 what I am talking about?
49 A. OK, or prevention, for that matter. For example, if a
50 very small increase in dietary fat -- just to take an
51 hypothetical example -- were to increase the risk of
52 breast cancer substantially, say, an increase from 10 per
53 cent of calories to 20 per cent of calories, if that were
54 to increase the risk of breast cancer, and if we were to
55 assume for the moment that that was a causal link, that is
56 not the same thing as saying that, perhaps, with colon
57 cancer there are changes along much higher levels. For
58 example -- perhaps I am not saying this as clearly as
59 I might.
60
