Day 017 - 25 Jul 94 - Page 25
1 breast cancer and compared these to the intake of women
who were found not to have malignant disease. No
2 relationship with fat was found.
3 Hirohata and his colleagues have studied fat intake in
relation to breast cancer in three groups of women with a
4 differing incidence of the disease. Japanese women in
Fukuoka, Japan (low risk), Japanese women in Hawaii
5 (intermediate) and Caucasian women in Hawaii (high risk).
No significant differences were found between cases and
6 controls, whether surgical or neighbourhood, in any of the
three groups in their mean intake of total or saturated
7 fat".
8 Given what Kolonel thought he had found earlier on in
relation to Hawaii, does that surprise you?
9 A. No, because, in fact, Kolonel himself admitted that
the association he detected was a very weak one, and this
10 is -- we were talking about statistics a little earlier
on, and whether these changes or associations could have
11 occurred purely by chance. What one is seeing in many of
these studies is that there is a wide range of what we
12 call confidence limits. In other words, you cannot comb
down the information enough to be sure that the difference
13 could not have arisen purely by chance.
14 So these two studies that you have been quoting are
overlapping each over; they are still within the range of
15 variability as determined in these two separate studies.
16 Q. Then I will go on: "Overall, the results of these
case-control studies provide relatively little support for
17 the hypothesis that fat is a cause of breast cancer.
Commentators have been quick to defend the hypothesis by
18 stressing the limitations of dietary case-control studies.
Not only may the presence of disease add to the obvious
19 difficulties of recalling past diet, but also, by
affecting current diet, it may unconsciously influence
20 memory of previous dietary habits. It has also been
suggested that those groups studied with negative results
21 may have contained insufficient variation in fact intake
for any real effect to be detected. Reference to the data
22 presented, however, shows this criticism to be unfounded
if the relationship shown in Figure 1", that was the
23 linear graph, "is genuine". Does that seem sense to you?
A. I think that is a very fair assessment of the problems
24 associated with these studies.
25 Q. Can I ask you this, Dr. Arnott: I do not know about the
medical world, but is there sometimes a tendency for
26 people who have hit upon the thought they have found an
attractive looking hypothesis or theory to be, what shall
27 I say, somewhat inpenetrable to intelligent criticism?
A. I think it is a general problem in medicine, not just
28 in these sorts of studies, but in reporting results of
treatment. It is always nice to be able report something
29 positive whereas, in fact, in reality, reporting a
negative result is equally as important. I would just
30 allude to the study that I was involved with on nutron
therapy.
