Double Trouble: Tracking the Life of a Tumor by: Michael Guthrie, R. Ph.
Deep inside the first cell of
a malignancy lurks a fatal flaw, a mistake in the control center, in the DNA
itself. It is amazing that this doesn't happen more often, as the incredible
'computer program' in the DNA contains millions upon millions of instructions,
and this information is passed on to new cells each time the cell divides. One
of those 'instruction sets' tells the cell to multiply only so many times and
then stop. This instruction set is actually much more complicated than that, but
for the purpose of this article, this description is adequate.
Rapid and
aggressive cell growth is actually normal in a few situations. One of the most
amazing is the growth of a full term baby in 9 months from a single cell.
Another is the repair of tissue damage, for example a cut to the finger. An
explosive growth of new cells fills in the gap very quickly and we heal.
However, in tissue repair, and in the intrauterine growth of babies, there is
control and orchestration. With cancer cells, the switch never turns off as it
does in normal growth. Other signals from adjacent cells that say 'enough
already' are also ignored. Normal boundaries that separate one tissue type from
another are also crossed by the wildfire cell growth. Normal cells receive (and
obey) all sorts of messages that are designed to keep this from happening.
Fast growing tumors double around once or twice a month, while slower
growing tumors may take up to 6 months to multiply. The mathematics of the
growth is exponential. After around 20 divisions, the one cell has grown to
around a million cells BUT it is still undetectable. At this point the tumor is
about the size of a large pinhead.
Most tumors are not diagnosed until
they are comprised of around one billion cells. This would take about two and
one half years if the cell divided once per month. This would represent 30
doublings. At 40 doublings, the tumor would be around 1 trillion cells and weigh
around 1 kg, which is 2.2 pounds. At 42 doublings, the body could not survive
(the body can only tolerate around two or three kilograms of tumor mass before
death occurs). If we consider a malignant cell that is doubling once per month,
the tumor has become lethal in around three and a half years. Most of you have
probably realized by now that the tumor is 75% of the way towards lethality
before it is detected, and by this time, it is quite possible that the tumor has
seeded into new areas of the body, where new tumor masses are being established.
One clear message arises from this discussion: early detection is vital;
therefore, early detection has a tremendous impact on survivability.
Mammograms and other diagnostic tools should help in the war on cancer.
If prevention is the most important weapon in our arsenal, then the second is
quite likely early detection. It is important to take advantage of the tools at
your disposal to detect cancer before the mass has a chance to cross into
lymphatic or blood circulation where it can send out 'seeds' that will establish
new tumors.
