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
