Day 017 - 25 Jul 94 - Page 05

     
     1   MR. JUSTICE BELL:  What was the last one?
              A.  From the blood forming tissues these are called
     2        leukeamieas.
 
     3   MR. RAMPTON:  So far as cancer of the breast is concerned, are
              you principally concerned with one particular type of
     4        cancer?
              A.  Cancer of the breast is an adenocarcinoma.  The breast
     5        in many respects is a modification of the skin, so it is a
              carcinoma.  The breast itself is not too dissimilar from
     6        other ducts which one can see on the skin surface, but it
              is obviously modified largely for the production of milk
     7        for the feeding of infants after childbirth.  But it is
              essentially a modification of the skin and therefore is an
     8        adenocarcinoma.
 
     9   Q.   What about cancers of the colon and rectum?
              A.  Right, well, these are also adenocarcinomas.  They are
    10        again carcinomas because they arise from a covering
              tissue, the surface -- we called it epithelium -- the
         lining epithelium, a lining covering of the intestine.
              Although they are adenocarcinomas, when you actually look
    12        at them under a microscope, the characteristics of the
              cells and structure of the tissue, the cancer itself, is
    13        quite different from that of breast carcinoma.  Although
              they are both called adenocarcinomas ("adeno" just means
    14        of glandular origin) they are quite distinct.
 
    15   Q.   We use carcinoma; it is a broad term but it has to do with
              the location of the tumour?
    16        A.  Yes, and the tissue of origin.
 
    17   Q.   Can you, before I come to aetiology, which is what we are
              concerned with in this case, just give us a brief summary
    18        of how a cancer, a tumour, is initiated, how it develops?
              A.  Right.  Well, I think the first thing I have to say is
    19        that a lot of the mechanisms in this are poorly
              understood.  A lot of what we believe about the process is
    20        inferred rather than there being actual, direct laboratory
              evidence, but it would seem that initially there is the
         process of initiation.  This implies that some change
              within the genetic mechanism within the cell itself is
    22        probably irreversible.  It can arise, we believe, for a
              variety of reasons such as radiation exposure, or it may
    23        be there is some genetic predisposition.  We are now
              believing there are certain oncogenes -- that is genes
    24        capable of promoting the development of tumours -- and
              that in life there are inhibitors as well promoters.  It
    25        is the balance which keeps us all healthy.  For some
              reason or another, the inhibition may be lost, allowing 
    26        the cell to change in this way. 
  
    27        Now because the cell changes and is initiated it does not
              necessarily need to form a cancer.  The cell can remain as
    28        it is unchanged and not have any influence on one's life
              expectancy, but then the next stage is believed to be
    29        promotion.  This is a reversible process.  It seems to be
              related not only to chemical exposure but perhaps viral
    30        infection or other biological factors, such as genetic
              predisposition, but the factors which are influencing