Cancer as parasite is an analogy I’ve been aware of, but I’ve never seen a cancer spreading between animals as a direct parasite (generally contagious spread is a result of viral hijacking causing changes in DNA that then leads to cancer).

Interesting — and potentially a disruptive way to think about cancer biology.

Scientists Report Findings on Origin of a Cancer in Tasmanian Devils – NYTimes.com.

The Tasmanian devil, the spaniel-size marsupial found on the Australian island of Tasmania, has been hurtling toward extinction in recent years, the victim of a bizarre and mysterious facial cancer that spreads like a plague.

Now Australian scientists say they have discovered how the cancer originated. The finding, being reported Friday in the journal Science, sheds light on how cancer cells can sometimes liberate themselves from the hosts where they first emerged. On a more practical level, it also opens the door to devising vaccines that could save the Tasmanian devils.

The cancer, devil’s facial tumor disease, is transmitted when the animals bite one another’s faces during fights. It grows rapidly, choking off the animal’s mouth and spreading to other organs. The disease has wiped out 60 percent of all Tasmanian devils since it was first observed in 1996, and some ecologists predict that it could obliterate the entire wild population within 35 years.

When the tumor disease was discovered, many scientists assumed that it was caused by a rapidly spreading virus. Viruses cause 15 percent of all cancers in humans and are also widespread in animals.

But subsequent studies failed to turn up a virus. Instead, Anne-Maree Pearse and Kate Swift, of the Department of Primary Industries, Water and Environment in Tasmania, discovered something strange about the tumor cells. The chromosomes looked less like those in the animal’s normal cells and more like those in the tumors growing in other Tasmanian devils.

In 2007, Dr. Belov and her colleagues compared DNA from 26 sick and healthy Tasmanian devils with DNA from the tumors. They found that cancer cells from different animals shared distinctive genetic markers not found in the animals themselves.

While doctors may carry scientific tomes in their heads and engineering marvels on and around their persons (although surprisingly few computers to date), the clinical practice of medicine is being rediscovered as an art, not a cookbook science. As new studies challenge the existing metrics evaluating risk through a black/ white approach dedicated to lowering intermediate clinical markers (see cholesterol for the otherwise low risk patient, glucose for Type 2 diabetics, BMI for the overweight, quantity of bloodborn “humors” to be released by lancet, etc)

Big lesson: Lower does not mean better

So, as we find out that cookbook medicine may actually be harmful in addition to being expensive, we have the same issue that is currently cracking the mortgage industry: evaluating and managing risk is hard and replacing underwriting with automation and customer service reps leads to problems when real judgment is required.

So where is that judgment required? Some docs, threatened by the emergence of retail clinics, believe it needs to be by a medical specialist in every encounter. John Wennberg and his group would say that its probably the opposite. And given the fundamental uncertainty, if you trust the experts in complex, hard to evaluate matters, which ones should you choose?

Today, it seems that the unknown biases of the “experts” who are the gatekeepers to the rest of the system unfairly impact the choices presented to individual consumers. For example, a rape victim going to a pharmacy for Plan B may be denied by the religious beliefs of the pharmacist. I wasn’t presented the choice of surgery for my blow-out fracture (with severe diplopia and an eye that moved as I sneezed) due to the beliefs of a particular department chairman. Its all too common to prescribe a polypharmacy prior to any serious attempt to counsel improvement in diet and exercise. Pregnant women often get told that they need to stay in bed for long periods due to spotting.

Since the “knowledge” of the experts often seems inadequate to give real statistics on the level of risk for individual situations, wouldn’t it seem better that we should know their biases prior to taking their advice? As a consumer-focused world evolves, the consumer knows which doc is a top 10% Lipitor prescriber as much as Pfizer does. Only then will the consumer be on equal ground and have the information to make their own health choices.