Day 036 - 13 Oct 94 - Page 39
1 A. Let me re-read that sentence and I will be glad to
2 provide an interpretation, if that would be helpful.
3 Yes. What he is simply saying is that the status of the
4 target organ -- by differentiation he means the degree to
5 which the cells have duplicated and become breast cells,
6 rather than a more immature type of cell -- that those
7 will influence the effect of fat on carcinogenesis,
8 presumably. It is certainly in line with what virtually
9 everyone would assume, is that carcinogens, in general,
10 will exert different effects at different stages of life.
11
12 Q. Can I read you the Conclusion? That will be my last word
13 before the break: "We have documented that the following
14 criteria must be satisfied in order for fat enhancement of
15 mammary carcinogenesis in the experimental model to be
16 expressed". Then he repeats what we have already read in
17 the abstract down to (c): "Previous history of pregnancy
18 and lactation". I will not read it again. "These
19 findings convincingly indicate that there are limitations
20 in extrapolating the results of fat and mammary
21 carcinogenesis studies in rodents to the human experience
22 of fat and breast cancer risk. Animal models in nutrition
23 and cancer research are useful to the extent that they
24 allow investigators to confirm and extend each other's
25 observations. They also provide an ideal opportunity to
26 design experiments so that independent variables can be
27 evaluated one at a time. Regardless of their deficiencies
28 they are often perceived as the litmus test to validate
29 certain correlative evidence from epidemiology studies.
30 However, in reality, animal models are woefully inadequate
31 to meet the challenge of offering definitive answers to a
32 complicated area of research as in human nutrition and
33 cancer aetiology. Given the spectrum of confounders that
34 are inherent in the association linking fat intake and
35 human breast cancer, including differences in lifestyle,
36 reproductive history, carcinogen exposure pattern, eating
37 habits, complexity of the total diet, and the contribution
38 of nonnutrients present in food, it is less than
39 comforting to realise that so little information is
40 available in the literature on the interactive effect of
41 dietary fat with these other factors which clearly have a
42 significant impact by themselves on the risk of breast
43 cancer".
44
45 Now it is that last bit that I wish to know, whether you
46 have any comment to make about it, Dr. Barnard?
47 A. Yes, I actually do have some comments on the
48 Conclusion paragraph.
49
50 Q. Yes. Can I ask you one thing?
51 A. Certainly.
52
53 Q. Can you not write on the witness' documents simply because
54 we have to use them again?
55 A. I was writing on my own pad.
56
57 MR. JUSTICE BELL: He has got his own pad.
58 A. Forgive me. I hope I have not made a strain mark on
59 your document.
60
