Day 033 - 10 Oct 94 - Page 21


     
     1        quite a different diet, have about half that prevalence of
     2        latent prostate cancers.
     3
     4        If one then also observes statistics on the likelihood of
     5        dying of prostate disease, the countries vary in precisely
     6        the same way; the higher the intake of fat, the more
     7        likely one is to -- the higher the rates of prostatic
     8        cancer deaths.
     9
    10   Q.   So on that second point, the promotive -- would that be a
    11        promotive effect of fat in the diet?
    12        A.  Yes.
    13
    14   MR. JUSTICE BELL:  So you have got initiation and promotion,
    15        but you have not got progression?
    16        A.  Right.  The same factors that promote the growth of
    17        cancer cells will, presumably, also encourage progression,
    18        so that one will see metastasis to distant sites as well
    19        as invasion of adjacent areas to the tumour.
    20
    21   MR. MORRIS:  Moving on to colon cancer, would you like to
    22        summarise the dietary implications of colon cancer?
    23        A.  Yes.  Here, both fat and fibre seem to play a role.
    24        Dr. Denis Burkitt (who I mentioned earlier) published
    25        observations based on his work in Africa where he was a
    26        missionary surgeon and became quite famous as a cancer
    27        researcher for identifying Burkitt's, what came to be
    28        known as Burkitt's lymphoma.
    29
    30        Following on the heels of that work, he became interested
    31        in why are certain cancers quite common in the United
    32        Kingdom and in other westernised countries, and why are
    33        they uncommon in Africa?  He published a review of
    34        epidemiological evidence in 1971, giving particular
    35        emphasis to the role of fibre; that a high fibre diet is
    36        associated with lower rates of colon cancer.  Also he
    37        hypothesised mechanisms by which that might operate; that
    38        carcinogens that may be in the digestive tract can be
    39        deluded by a high fibre intake.
    40
    41        A high fibre intake makes the stools considerably more
    42        bulky and the fibre absorbs water rather like a sponge
    43        soaks up water; the carcinogens are absorbed and deluded
    44        in the process.  That reduces the concentration of
    45        carcinogens on the wall of the large bowel.  This is the
    46        presumed mechanism, or one of the mechanisms.  However,
    47        since that time other mechanisms have been suggested and
    48        studied which I describe in my statement here.
    49
    50        The international comparisons parallel those with breast 
    51        cancer and prostate cancer in that countries that have a 
    52        higher fat intake have a higher rate of colon cancer in 
    53        general terms.  Likewise, countries that have a higher
    54        fibre intake have a lower rate of colon cancer.
    55        Case-control studies in which individuals who have cancer
    56        are then compared to individuals who are like them in
    57        other ways but do not have cancer, and in case-control
    58        studies, a study was done in Canada, for example, that
    59        showed an association between, on the one hand, fat,
    60        saturated fat, and total calories and cancer of the

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