Day 017 - 25 Jul 94 - Page 47
1 starting with the first complete paragraph: "Faecal bile
acids levels have been measured in high and low risk
2 populations".
3 MR. MORRIS: Where are we?
4 MR. RAMPTON: Page 599. "This epidemiological approach has
been utilized by several groups and strongly supports the
5 role of bile acids in large bowel carcinogenesis. It has
been suggested that increased consumption of meat and
6 hence animal fat would account for the high-risk
populations. There is a close relationship between per
7 capita meat intake and colorectal cancer incidence in
various populations. Seventh Day Adventists who consume
8 little or no meat show a relatively low rate of colorectal
cancer as compared to their fellow Americans. However, a
9 survey of dietary variations within Seventh Day Adventists
showed no relationship between meat consumption and large
10 bowel cancer. New Zealand Maoris enjoy a high intake of
fat and protein, yet the incidence of colorectal cancer is
11 low in this group.
12 It is relevant also that dietary manipulation has failed
to influence the bacterial flora of the large intestine.
13 Case control studies (in which each patient with
colorectal cancer is matched to a 'normal' control) have
14 usually failed to support a link between either meat
intake or faecal bile acid levels and colorectal cancer.
15 It is important that patients with colorectal cancer are
carefully selected for such studies. Patients with cancer
16 may have modified their diet and the presence of liver
metastases" -- those are substances, are they?
17 A. No. Liver metastases are where the cancer has spread
to the liver and formed secondary growth within the liver
18 itself. So a metastases is a secondary growth which is in
fact one of the characteristics of cancer as I described
19 this morning.
20 Q. I will finish the sentence and then I will ask you about
it. "The presence of liver metasates could influence bile
21 acid metabolism." Is that so far as your expertise is
concerned a correct statement of affairs?
22 A. Well, it could do. In reality we are able to live
with quite a lot of our liver involved by cancer and still
23 lead, you know -- the ostensible test one can perform on
patients show little abnormality. But the point he is
24 making is that when you are looking at patients with
cancer there are other factors which may come into play,
25 such as have they modified their diet themselves. We have
talked about this morning with regard to breast cancer;
26 they recall of previous diet may be influenced by the fact
that they know now they have cancer. The actual natural
27 history and behaviour of the tumour itself may in some way
influence metabolism, such as if you get deposits within
28 the liver, the liver is undoubtedly affected and it may,
therefore, influence the metabolism of the bile acids.
29
Q. He goes on, Dr. Morson: "It has been argued that the
30 failure of case control studies to support dietary and/or
faecal bile acid hypothesis may reflect the confounding
