Sunday, May 10, 2015

Little cancers and turtles

Very quick thoughts in follow up to the last blog on cancer metastasis.  In this article  ("Overkill: America's Epidemic of Unnecessary Care" from the 11th May New Yorker), Atul Gwande questions many medical procedures as unnecessary.  I loved the piece and I buy his arguments.  Referring to a recent book by Dr. H. Gilbert Welch, from Dartmouth Medical School ("Less Medicine, More Health," published by Beacon Press, 2015), he calls the cancers that don't appear to be doing much, and therefore may not need action,  'turtles' as opposed to the rabbits that race ahead and need to be stopped in their tracks. Turtles don't need the same level of diagnostic technology as the rabbits, but modern medicine tends to throw everything at everything, often at great cost and even detriment to the patient. 

What stuck with me about this article though, was the reference to a "microcarcinoma" in a patient's thyroid.  He explains that as many as a full third of the population has microcarcinomas in their thyroids but only 1 in 1000 die from thyroid cancer each year.  Since it is only the relatively rare microcarcinoma that takes off like a rabbit and becomes deadly, some experts suggest that microcarcinomas not be called cancers at all and currently, guidelines do not recommend treatment.  This reminds me of a study I read a few years ago that found breast cancer cells to be highly prevalent in women over 65 ( it could have been 60- I don't remember exactly), with relatively few turning into actively progressing cancer.   These are not discovered until autopsy when the patient has died of something unrelated.
So if these observations are correct-and I have no reason to suspect they are not- then we are all potentially walking around with cancer in situ, with most of these cheeky little cells not doing much more than scaring the pants of the pathologist (and eventually the patient) that comes across them.  The procedures to remove some of these microcarcinomas are more risky that the cancer cells themselves, as Dr. Gwande points out. So why not leave them alone until they start to act up and show signs of causing trouble?  The answer is obvious; because we don't know if or when that will happen, and by the time we find out, it may be too late.  We can see why there is a tendency to act versus not act, when these characters are found.  To change the paradigm we would have to find a means to non-invasively monitor these cells for signs of growth and movement.

In order to do this we need to answer a few questions:

  • How does a micro cancer cell 'decide' to take off and grow? What are the stimuli and how does the transition begin? How long does it take to become a fully fledged, rapidly dividing menace?
  • Are there plasma factors that can be measured when this happens?
  • How does a cell ' decide' to metastasize. How long does it take to create the mechanism to do so?
  • Once the pieces are in place, and the cancer cells leave the primary site, how do they decide where to settle, and how long does it take to successfully seed the new site?
It seems there is a temporal aspect to this (remember in the last blog, the metastatic seeding seemed to occur in waves).  I know there are some very big brains working on these questions and I am scraping the surface only.  This blog is really me thinking-out-loud on my own journey to stake out the heart of cancer and it's wily ways.  


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