Day 023 - 13 Sep 94 - Page 10
1 rather than younger; the older you are when you have your
2 first child, the greater the risk you have of developing
3 breast cancer. Also there appears to be a protective
4 effect if you have more children rather than fewer
5 children. Again this is something which, you know, fewer
6 children are seen in developed countries because couples
7 work. There are social factors other than dietary
8 factors. So, yes, there are cancers where, like breast
9 cancer, other factors than diet have been implicated to
10 explain the differences which occur in different parts of
11 the world.
12
13 Q. What about colon cancer?
14 A. Well, this again is more difficult to know but, as we
15 were saying yesterday, there may be some genetic factor
16 which we understand poorly. Polyposis coli, this
17 genetically determined condition is something which one
18 tends to see in western countries, though this may be a
19 problem of information retrieval rather than anything
20 else, because we also said yesterday in under-developed
21 countries their information systems are not so good.
22
23 Colon cancer is the great enigma, in that people have
24 argued just about everything as being involved in the
25 causation of colon cancer, but the honest answer to it all
26 is that we do not know.
27
28 Q. But the alternative you are putting forward to diet is
29 genetics in terms of colon cancer?
30 A. As I said yesterday, we do know that if -- say your
31 mother had developed colon cancer, the risk of you
32 developing colon cancer would be increased at least two to
33 four fold, which is a substantial increase. Now, we
34 cannot actually identify a specific genetic abnormality to
35 account for that, but this relationship is so consistent.
36
37 Q. But it could equally be that my mother teaches me how to
38 cook and what sorts of things to eat?
39 A. The relationship is irrespective of dietary patterns.
40 People have looked at this and tried to say, "It is this.
41 If you are used to a high fat diet, the same risks will
42 act on you and your mother". But they have also looked at
43 people with so-called "low risk diets". This relationship
44 still stands. There is an increased risk of a blood
45 relative getting cancer if another one has developed
46 cancer at some time in the past.
47
48 Q. There is also the migration studies where people live in a
49 country with low a risk, migrate to a country with a
50 higher risk where there has not been any history before
51 they start -----
52 A. But the other factor is that it is not only diet that
53 changes when people move to these countries, their
54 lifestyle changes. There is an interaction of factors
55 here. Diet may be one -- I am not saying it is not -- but
56 it is not as straightforward as only diet being implicated
57 in what happens to people when they move countries.
58
59 Q. What studies have indicated other lifestyle factors apart
60 from diet?
