Monday, January 5, 2015

Human diseases are not caused by bad luck

Earlier this week, I posted a blog criticizing the conclusions reached in a highly publicized paper written by a group of scientists at Johns Hopkins Medical Center. The authors conclude that "bad luck", rather than environmental or genetic causes, is responsible for the bulk of human cancers. My prior blog post explained why Hopkins is wrong.

After the blog was written, I got some very interesting feedback from a LinkedIn group (Science writers). Much of the discussion centered on the meaning of "luck", as it applies to biological processes.

Terms such as "luck", "accident", "misfortune", and "unpredictable" are often used, inappropriately, to describe complex events that we do not fully understand. For example, we speak in terms of "motor vehicle accidents" to describe vehicular crashes, even when we have discovered non-accidental causes (e.g., driving while intoxicated, driving on the wrong side of the road, failure to yield). We use the term "cerebrovascular accident" to describe strokes, even in individuals who have abundant risk factors (e.g., high blood pressure, e.g., occluded carotid artery). When we come down with a cold, we often say that it was our bad luck or our misfortune to get sick, even when we know that the cold was caused by a virus.

When we flip a coin, we like to think that the outcome occurs randomly, because there is a 50% chance of heads or of tails. But we all know, at some level, that the outcome of the toss is predetermined at the moment that the coin flips into the air. The laws of physics come into play, with a complexity that defies human prediction. Coin tosses, and roulette spins, are examples of processes that can be modeled, mathematically and intuitively, as probabilistic events. But we shouldn't confuse a probabilistic model with a physical reality.

Biology and medicine are replete with examples of phenomena that were attributed to "bad luck" until we finally determined their causes. For example, until the dawn of the twentieth century, the cause of malaria was unknown. There must have been something in the air (mala aria = bad air in medieval Italian). In 1880, Laveran identified the causative agent, a protozoan, in the blood of affected patients, for which he was awarded the Nobel prize in 1907. Through the centuries, people suffering from infectious diseases, vitamin deficiencies, and environmental toxins were considered "unfortunate", meaning "without luck."

Do not presume that modern-day scientists are too enlightened to be taken in by "chance" phenomenon. For many years, medical scientists sought a cause for sudden infant death syndrome (SIDS). Children were dying in their cribs, unpredictably, as though they had the bad luck to just stop breathing. In the past half century, we have learned that the majority of cases of SIDS are associated with sleeping conditions that limit the infants ability to breathe (e.g., sleeping on stomach, in hot room, with overabundance of soft bedding, etc.).

Today, cancer has become the quintessential "bad luck" disease. The literature gives us lots of examples of "bad luck" cancers that transformed into "specific cause" cancers, when we studied the data.

For example, In a landmark paper published in 1971 by Herbst and coworkers, the authors found an increase in the number of young women who developed an extremely rare cancer: clear cell adenocarcinoma of the cervix or of the vagina. The mothers of these young women had ingested a nonsteroidal synthetic estrogen (diethylsilbestrol, DES) during their pregnancies. In utero exposure to the drug caused a specific rare tumor to occur in the daughters. The offspring were classic "bad luck" cancer victims, having done nothing to put themselves at risk. Herbst had to go back a generation to find the real cause.

Women who developed mesotheliomas, a very rare cancer, in the 1970s and 1980s, were also the victims of "bad luck", until cancer epidemiologists found the common factor that linked these cases. These women had washed the asbestos-laden clothes of their fathers or husbands, who worked in the shipyards during World War II. Their brief exposure to asbestos resulted in mesotheliomas 20+ years later.

Much of what we observe in biology and medicine looks exactly like luck... until we understand the cause. The effect of "bad luck" hypotheses, as they apply to biology and medicine, is to halt scientific progress. Why would scientists waste their time looking for the causes of cancer, if cancers are caused by "bad luck"? The U.S. Environmental Protection Agency certainly can't protect us from bad luck!

I urge everyone reading this blog to also read my prior blog, which provides a rebuttal to the Johns Hopkins "bad luck" cancer hypothesis.

- Jules Berman

tags: johns hopkins, cancer news, bad luck, data repurposing, opinion, criticism, carcinogenesis, rare cancer, rare diseases, cancer incidence, comparative carcinogenesis, Jules J. Berman, Ph.D., M.D., cancer research, new findings, mutation rate, rebuttal, stem cell renewal, probabilistic models, data modeling, randomness, chance, misfortune, accident, unpredictable