Day 034 - 11 Oct 94 - Page 12
1 impression it makes on me and the impression it has made
2 on the Surgeon General.
3
4 MR. MORRIS: Yes.
5
6 MR. JUSTICE BELL: That is not to deter you from asking any
7 other questions.
8
9 MR. MORRIS: Would you like to go through the cohort studies?
10 A. Yes. Briefly to describe, cohort studies simply mean
11 that a population is identified, their diets are assessed,
12 they are then followed prospectively and the incidence of
13 cancer, the prevalence of cancer rather, is assessed at a
14 later point. Four such studies have been done. Three of
15 them did not detect an association; one, however, did and
16 that was the relationship with meat -- meat intake and
17 breast cancer.
18
19 Now, it has been already described and is, I presume, well
20 understood that cohort studies, where the individuals do
21 not vary a great deal in fat intake, are not likely to
22 show an association. Indeed, that has been a common
23 criticism of Willett's study, also of Jones's study, that
24 in each case there was simply very little difference
25 between the subjects and it was impossible to find a
26 statistical relationship. I believe we discussed that
27 some yesterday.
28
29 Q. It may be helpful to comment a bit on the animal studies
30 very briefly -- you did mention them -- then ask for your
31 overall -----
32
33 MR. JUSTICE BELL: What would help me, I think, is -- I do not
34 know, I have not formed a view yet on whether table 4-7 is
35 a useful bird's eye view. But, insofar as it does provide
36 a bird's eye view of a large number of papers, what does
37 it demonstrate or mean, if anything, to Dr. Barnard?
38
39 MR. MORRIS: Just on the subject of is it a useful bird's eye
40 view, is this a kind of objective view that the Surgeon
41 General is looking at the best studies?
42 A. As of 1988, I would say yes.
43
44 Q. OK. So, in your opinion, is this the best table that
45 could be put down on one piece of paper at that time?
46 A. I think it is a reasonable summary of the research to
47 date at that time. It does not -- it is limited -- this
48 only looks at epidemiologic studies. It has to be
49 understood this does not look at any of the evidence on
50 mechanisms, for example, studies in which high fat diets
51 caused obesity and in which obesity was linked to cancer,
52 or in which high fat/low fibre diets altered the age of
53 menarche and in which lower age of menarche increased the
54 risk of cancer; such studies would not be included here.
55 Studies showing links between higher oestrogen levels in
56 the blood and a higher risk of cancer and dietary links.
57 Those would not be included here. Animal studies are not
58 included here -- this is no more than the epidemiologic
59 data.
60
