Day 030 - 03 Oct 94 - Page 49


     
     1        works.
     2
     3        I will not go into too much detail on this, but what they
     4        did was a sophisticated epidemiological exercise which
     5        started off quite simply.  What they did was to compare
     6        the rates of death in cancer registries where the rates of
     7        death from specific cancers, the lowest to the reverse,
     8        those cancers registries where the rates of death were
     9        highest and, in common with other research workers whose
    10        conclusions chose are regarded as reliable, they said that
    11        it is fair to say that environmental factors account for
    12        80 to 90 per cent of all cancer deaths, that is to say,
    13        the pure genetic connection is not very substantial in the
    14        case of cancer.
    15
    16        What then becomes more sophisticated is how do you
    17        calculate within the environmental causes the dietary
    18        factor?  That is really the subject of this large book
    19        which you may be happy to know is not in court today, but
    20        the conclusion they came to was that alcohol reliably
    21        could be said to cause something like three or four per
    22        cent of all cancer death.  That was a pretty hard figure.
    23        Again, I think that has been referred to in evidence
    24        earlier in this case; whereas the diet as a whole they
    25        proposed an extremely broad range of between ten and 70
    26        per cent, but had some reason to believe that roughly the
    27        mean figure of 35 per cent or roughly over a third of all
    28        deaths from cancer could be attributed to diet.
    29
    30        That is a negative way of putting it.  You can put it
    31        positively of course and, putting it crudely, what they
    32        were suggesting is that if you eat the wrong kind of diet,
    33        you are going to increase your chance -- your risk of many
    34        cancers.  If you eat the right kind of diet, you thereby
    35        decrease your risk.
    36
    37        The extent of the risk depends on the cancer.  In the case
    38        of lung cancer, for example, there is good evidence (and
    39        was then) that vegetables and fruit or, rather, particular
    40        chemical constituents of vegetables and fruit are powerful
    41        protectors against all cancers, including lung cancer, but
    42        it is not reckoned that amongst smokers you are going to
    43        reduce your chances of lung cancer very much if you eat
    44        lots of fruit and veg or if you drink orange juice or
    45        whatever; whereas stomach cancer -- not mentioned so far
    46        today -- and colon cancer and, to a lesser extent, breast
    47        cancer and also prostate cancer are regarded as very
    48        heavily influenced by diet of the ones I have mentioned,
    49        stomach cancer and colon cancer most of all.
    50 
    51   Q.   So this approach of identifying percentages of cancers 
    52        that could be reduced with dietary changes, has that 
    53        approach continued -- is there a consensus emerging about
    54        that?
    55        A.  There is not consensus -- it depends what you mean by
    56        "consensus".  Yes, there is consensus if you mean that
    57        Doll and Peto's estimate or, as they would call it, I
    58        think, guesstimate of this very wide range is constantly
    59        cited; it is cited by government, it has been referred to
    60        by the chief medical officer in addresses he has given,

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