Day 035 - 12 Oct 94 - Page 57
1 disease, greatly increase the risk but because of their
2 rarity these account for a very small proportion of cases.
3 The rare familial polyposis syndromes are associated
4 with high risk, but also contribute only slightly to the
5 overall incidence of colon cancer. The presence of
6 adenomatous colon polyps, which can be considered as
7 precursor lesions, is associated with an elevated risk of
8 colon cancer. Because the polyps can be examined directly
9 by endoscopy, they provide a way of studying the
10 progression to colon cancer that does not exist for breast
11 cancer." So far so good or not?
12 A. Sure, yes, that is fine.
13
14 Q. "Diet and cancers" -- sorry, do you want to add something?
15 A. His characterisation of polyps and so forth is fine.
16 When he talks about "few specific risk factors for colon
17 cancer have been established", his first sentence, that is
18 a judgment call he is making, seemed to minimise the risk
19 factors for colon cancer.
20
21 Q. He expands on this later on?
22 A. Very good.
23
24 Q. As you will see. It is quite a long article. We will
25 have to read quite a lot of it: "Diet and cancers of the
26 breast and colon - dietary fat and breast cancer. For the
27 last decade, the dominant aetiological hypothesis for
28 breast cancer has been that high fat intake, and animal
29 fat in particular, is the primary cause of the large
30 differences in rates between countries. This notion is
31 based largely on two lines of evidence: striking
32 international correlations (approximately 0.8) between per
33 capita consumption of fat and breast cancer rates, and
34 animal experiments in which diets high in fat increase the
35 occurrence of mammary tumours. Subsequent evidence has
36 not, overall, supported this hypothesis." As to 1989,
37 Dr. Barnard, what comment about that statement?
38 A. Well, this is a common sort of thing that Walter
39 Willett would say.
40
41 Q. Very well. "It is tempting", says Walter Willett, "to
42 draw causal inferences from the international
43 correlations, but these studies provide only weak evidence
44 because the actual cases might involve many other factors
45 related to economic development. Factors such as physical
46 activity, reproductive variables, body composition at
47 different times in life and energy balance, are
48 particularly difficult to measure and control in
49 correlational analyses. A recent survey of cancer rates
50 in 65 rural counties in China with similar low levels of
51 economic development" -- this, I can tell you, is a study
52 I think it is called the China Health Study by Professor
53 Campbell, whom I am sure you are familiar with?
54 A. Yes.
55
56 Q. I have also to tell you that Professor Campbell has said
57 that Dr. Willett has misrepresented the effect of his
58 findings in this article?
59 A. The thought did cross my mind as you were reading.
60
