Day 033 - 10 Oct 94 - Page 14
1 of studies that might shed further light on this. For
2 example, within Japan itself, where everyone is breathing
3 the same air and drinking the same water, we presume, and
4 has similar access to medical care and other factors,
5 researchers have looked at dietary factors and their
6 relationship to cancer. Indeed, they found that higher
7 fat intake is linked -- a higher fat intake goes hand in
8 hand with a higher risk of breast cancer.
9
10 Hirayami's study of 1978, for example, is one that I refer
11 to, where within Japan Japanese women who eat meat daily
12 have an 8.5 times higher risk of breast cancer compared to
13 Japanese women who rarely or never eat meat. Parallel
14 with this, as the Japanese diet has changed, since World
15 War II the fat intake has doubled. The breast cancer rate
16 has also gone up.
17
18 This eliminates genetic factors from consideration for
19 those changes. There is a role for genetics in breast
20 cancer. However, when you have a population that has
21 remained the same and their cancer rate has gone up rather
22 dramatically, their DNA, one cannot say, has somehow
23 undergone some massive change or, at least, they are not
24 hereditary factors that are being handed down in some
25 novel way, one has to presume that it is an environmental
26 factor, and the key one seems to be fat.
27
28 So far I have talked about international correlations and
29 within country comparisons. The same was done, by the
30 way, in Hawaii, in the studies of Kolonel, showing that
31 within the same geographic area, where again one would
32 have similar exposure to carcinogens and pollutants, again
33 a high fat intake was linked with a high rate of breast
34 cancer.
35
36 Migrant studies also have shown the same sort of thing;
37 that people who change from one geographical location to
38 another quite quickly adopt the diets of their newly
39 adopted land and tend to assume the risk of breast cancer
40 of that area.
41
42 Another type of study is the cohort study. In a cohort
43 study one identifies a group of subjects, tracks, or
44 identifies what their diet may be, what their diet is, and
45 then simply follows them prospectively to see their rate
46 of cancer. Hirayami, who I mentioned earlier, did that
47 type of study within Japan. It was a cohort study.
48
49 I should say that not all studies have shown this. Some
50 have not shown an association between fat and cancer; some
51 have shown an association, but have not been able to prove
52 that it is -- whether it is due to chance or not.
53
54 Kinlen's 1982 study, for example, showed differences
55 between different groups in their breast cancer risk
56 compared to -- in relation to their intake of meat.
57 However, the study was small and did not then reach
58 statistical significance, even though there was a
59 difference in the group.
60
