THE
CANCER PROBLEM 113
growth
of which was favoured by the absence of an “embryo” or sexual generation.
At
that time there appeared to be one hopeful outlook for cancer research along
the lines of embryology. It was that in every normal development the
trophoblast, which in the absence of a completed embryo might become a
malignant tumour, chorio-epithelioma, was invariably suppressed and
degenerated. The task was to find out how this came about; for there appeared
to be good reason for the hope, if not for the sure belief, that the factor or
factors which brought about this result in normal development might also be
potent when directed against an irresponsible trophoblast or cancer. To find
these factors would be the solution of a general scientific problem of which,
apparently cancer was but a special case. These factors have now been found,
and in consequence cancer ceases to be a problem for the embryologist. A
scientific solution of a certain problem has been obtained; whether or not this
be at the same time a solution of the cancer problem in its medical aspects
would not be for the embryologist to predict. He can only guarantee the truth
of the embryological findings and conclusions, and maintain that these would
remain, even though they should fail utterly when applied in the treatment of
malignant tumours.
The
change in nutrition initiated at the critical period in vertebrate animals,
from fishes to man, is based in the commencing functional activities of the
pancreatic gland or sweetbread. This introduces an alkaline digestion by means
of the pancreatic juice with its various ferments. But what of the pre-critical nutrition ? There are many ways in
which this might be investigated. One might examine normal trophoblast, cancer
or sarcoma, blastoderm of a fish—such as the skate—cleaved eggs of an
amphibian, or