Day 254 - 22 May 96 - Page 30
1 this in the same order, it says underneath the chart that
2 'relative risks are adjusted for the following variables.
3 Age at menarche', then it goes through some other ones,
4 'body mass index', more other adjustment, 'fibre intake,
5 and energy intake'. So, the risk adjustments were made on
6 all of those, the relative risk adjustments were made on
7 all those things, yes?
8 A. What they are trying to do by this, I am afraid ----
9
10 Q. Could you just answer yes or no and then expand if you
11 want?
12 A. Can you repeat the question?
13
14 Q. It says 'the relative risks are adjusted for the following
15 variables'; that means the risks in the chart above, yes?
16 A. Yes.
17
18 Q. They have all been adjusted for all of those things, is
19 that right?
20 A. The relative risks, yes.
21
22 Q. Yes, and that includes age at menarche, body mass index,
23 fibre intake, and energy intake?
24 A. Yes.
25
26 Q. Which are all things which are influenced by diet?
27 A. What they are trying to do here is to take out factors
28 which might confound the results, they are trying to look
29 at a specific relationship, which is the relationship
30 between fat and breast cancer, and, as we all know, all of
31 these other factors which, at least a lot of them, we
32 believe may be important. I am not sure about education
33 and so on, but they have looked at things like social
34 status, mother having had breast cancer, a sister having
35 breast cancer, things like hormones, oral contraception and
36 so on.
37
38 They have tried to look at things which might possibly
39 influence the risk of a patient having developed breast
40 cancer, and what they do in this statistical analysis is
41 adjust things so that you can look at comparable groups of
42 patients who have this relative effect from, say, age at
43 menarche at less than 11 or greater than 15 years, and they
44 will then compare people with breast cancer and those
45 without breast cancer to see if there is any difference
46 related to the intake of fat.
47
48 So, they are trying to get rid of these confounding
49 variables so they can look at the one thing which is the
50 purpose behind this paper, which is, is there the
51 relationship between fat and breast cancer?
52
53 MR. JUSTICE BELL: Yes, but Ms. Steel's point she is putting to
54 you is that some anyway of the confounding variables may
55 have an element of fat involved in them, fat intake
56 involved in them. Do you see? So, you may be taking away
57 some of the effect of fat intake in allowing for those
58 confounding variables. What I cannot see is whether some
59 statistical account of that is taken in the method of
60 discounting for the confounding variables so that, for
