Day 036 - 13 Oct 94 - Page 24
1
2 Q. Yes, I am sure that is right. More important, perhaps, is
3 this, Dr. Barnard: Do you notice that Dr. Kushi and his
4 team, at least, are shy of proposing that the strong
5 ecologic associations are causal?
6 A. He is not saying -- I would agree with you in that he
7 is saying that it has not been determined that they,
8 indeed, are causal, to use his words, regarding
9 "determine" and "are causal". That is what he is saying.
10
11 Q. He is not even certain that it will be possible to
12 determine that; he says that it may be possible, whether
13 they are causal, to determine whether they are causal, is
14 he not?
15 A. Let me try to be very clear about what, at least,
16 I have been trying to talk about over the past several
17 days that I have been here. The links are established --
18 I think we all agree on that -- between a
19 high-fat/low-fibre diet and breast and colon cancer.
20
21 Q. I do not want to be impolite, Dr. Barnard, but the word
22 "link" is one which is capable, at any rate, of more than
23 one meaning; might we use the word "association"?
24 A. We would agree on the association, and the association
25 that is assumed is a causal one. However, it has not been
26 definitively proven to be causal. I think what Dr. Kushi
27 here is saying is quite right in that regard.
28
29 Q. So long as one interprets him in that way?
30 A. Well, let me make another couple of points which may
31 be helpful in the interpretation of the study. First of
32 all, it is useful to note that what Dr. Kushi is
33 describing here is epidemiologic only, and he is not
34 characterising bio-chemical mechanisms, so he is not
35 attempting to link cause-and-effect through such factors
36 as obesity or menarche, which we have discussed in
37 tremendous detail earlier.
38
39 What Dr. Kushi, as an eminent and I think very well
40 qualified epidemiologist, is saying is that when one
41 strips away the mechanistic links which we know do exist,
42 and which we have described, between, say, a high-fat diet
43 increasing the risk of obesity (which it clearly does)
44 which increases the risk of breast cancer (which it
45 clearly does), if we do not look at those mechanisms but
46 we simply look epidemiologically that the association may
47 be causal based on that evidence alone.
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49 The second point that has to be made is that his data, as
50 he has interpreted them, do indicate an increased risk
51 with increased fat intake. However, as he has aptly
52 described, the figures do have to be adjusted based on the
53 statistical model that one uses.
54
55 The next point that is important, as he has described his
56 population he believes is, perhaps -- well, not perhaps --
57 was indeed an imperfect one. His follow-up period is
58 also worth noting. It was a four year study, which is
59 very short, and we are talking about a chronic disease,
60 and it would be, indeed, quite surprising to find a very
