Day 017 - 25 Jul 94 - Page 46


     
     1        pathnogenesis.  Is he Doctor Morson, Professor Morson?
              A.  He is doctor Morson.
     2
         Q.   Writes: "Multiple factors are involved in the aetiology of
     3        colorectal cancer just as multiple steps are implicated in
              its pathogenesis. It is probable that both environmental
     4        and constitutional factors are interwoven within the
              aetiology but that the precise composition of events
     5        varies from one individual to another.
              From one individual to another.  Thus neither one factor
     6        nor one set of factors will underlie the aetiology of all
              cases of colorectal cancer."  That unwillingness to
     7        generalise, is that more or less your position?
              A.  It is indeed.  I think this is a very fair statement
     8        of the current position regarding our knowledge of the
              aetiology of large bowel cancer.
     9
         Q.   "Cancer is ultimately a disorder at the level of the gene,
    10        though behaviour of a malignant cell will depend also upon
              the mode of gene expression. This may be influenced by
    11        environmental factors.  The initiated state may in some
              instances be constitutional, perhaps due to the
    12        inheritance of a transforming or a potentially
              transforming gene (oncogene) or the inherited loss of a
    13        growth controlling gene." That, Dr. Arnott, is what you
              told us this morning I think?
    14        A.  That is correct, yes.
 
    15   Q.   Can we jump down a page then on page 599 to Environmental
              Factors:  "The considerable geographical variation in the
    16        incidence of colorectal cancer signals the importance of
              environmental factors in the aetiology of the disease.
    17        This variation does not appear to be related to racial
              differences as migrants from low- to high-risk areas
    18        acquire the pattern of incidence appropriate to their
              adopted country.  The attention of epidemiologists and
    19        experimentalists has focused mainly upon diet.  Blame has
              been placed upon the excess consumption of meat and animal
    20        fat, refined carbohydrate or beer at the expense of fibre,
              vegetables and trace elements." Is selenium a trace
    21        element?
              A.  Yes, it is
    22
         Q.   Has there been any suggestion that calcium might be a
    23        protective or inhibiting agent?
              A.  Yes.  There is more recent evidence which suggests
    24        that calcium may indeed be a possible inhibiting agent as
              far as the development colorectal cancer is concerned.
    25
         Q.   "It is likely that the various dietary hypotheses are 
    26        interrelated and that a summation of factors is ultimately 
              responsible for the provision of a carcinogenic 
    27        microenvironment." When Dr. Morson uses the word
              "microenvironment", what do you understand him to mean?
    28        A.  I think what he is talking about is an environment
              within the bowel itself, something which is existing there
    29        but not necessarily existing throughout the remainder of
              the body.
    30
         Q.   Can we then pass over to the opposite column on page 599

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