Day 036 - 13 Oct 94 - Page 24


     
     1
     2   Q.   Yes, I am sure that is right.  More important, perhaps, is
     3        this, Dr. Barnard:  Do you notice that Dr. Kushi and his
     4        team, at least, are shy of proposing that the strong
     5        ecologic associations are causal?
     6        A.  He is not saying -- I would agree with you in that he
     7        is saying that it has not been determined that they,
     8        indeed, are causal, to use his words, regarding
     9        "determine" and "are causal".  That is what he is saying.
    10
    11   Q.   He is not even certain that it will be possible to
    12        determine that; he says that it may be possible, whether
    13        they are causal, to determine whether they are causal, is
    14        he not?
    15        A.  Let me try to be very clear about what, at least,
    16        I have been trying to talk about over the past several
    17        days that I have been here.  The links are established --
    18        I think we all agree on that -- between a
    19        high-fat/low-fibre diet and breast and colon cancer.
    20
    21   Q.   I do not want to be impolite, Dr. Barnard, but the word
    22        "link" is one which is capable, at any rate, of more than
    23        one meaning; might we use the word "association"?
    24        A.  We would agree on the association, and the association
    25        that is assumed is a causal one.  However, it has not been
    26        definitively proven to be causal.  I think what Dr. Kushi
    27        here is saying is quite right in that regard.
    28
    29   Q.   So long as one interprets him in that way?
    30        A.  Well, let me make another couple of points which may
    31        be helpful in the interpretation of the study.  First of
    32        all, it is useful to note that what Dr. Kushi is
    33        describing here is epidemiologic only, and he is not
    34        characterising bio-chemical mechanisms, so he is not
    35        attempting to link cause-and-effect through such factors
    36        as obesity or menarche, which we have discussed in
    37        tremendous detail earlier.
    38
    39        What Dr. Kushi, as an eminent and I think very well
    40        qualified epidemiologist, is saying is that when one
    41        strips away the mechanistic links which we know do exist,
    42        and which we have described, between, say, a high-fat diet
    43        increasing the risk of obesity (which it clearly does)
    44        which increases the risk of breast cancer (which it
    45        clearly does), if we do not look at those mechanisms but
    46        we simply look epidemiologically that the association may
    47        be causal based on that evidence alone.
    48
    49        The second point that has to be made is that his data, as
    50        he has interpreted them, do indicate an increased risk 
    51        with increased fat intake.  However, as he has aptly 
    52        described, the figures do have to be adjusted based on the 
    53        statistical model that one uses.
    54
    55        The next point that is important, as he has described his
    56        population he believes is, perhaps -- well, not perhaps --
    57        was indeed an imperfect one.   His follow-up period is
    58        also worth noting.  It was a four year study, which is
    59        very short, and we are talking about a chronic disease,
    60        and it would be, indeed, quite surprising to find a very

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