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

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