SciAm: “Most Cancer Cases Arise from “Bad Luck” Environment and heredity are smaller players than researchers previously believed”

From Friday's daily email which Scientific American sends to anyone interested. Science marches on as underlying beliefs get overthrown.

It was the study that launched hundreds of scientific rebuttals, insinuations that the authors had been paid off by the chemical industry, and charges that it was a “massive” stunt “hidden behind fancy numbers of doubtful quality.” The claim that sparked this controversy? That “bad luck,” more than environmental factors or inherited genes, affects whether someone develops cancer, implying that preventive efforts from smoking cessation to environmental cleanups were largely pointless.

Now the authors of that 2015 paper are back. In a study published on Thursday in Science, they double down on their original finding but also labor mightily to correct widespread misinterpretations of it. This time, using health records from 69 countries, they conclude that 66 percent of cancer-causing genetic mutations arise from the “bad luck” of a healthy, dividing cell making a random mistake when it copies its DNA.

The scientists go to great pains to explain that this doesn’t mean that two-thirds of cancers are beyond the reach of prevention. But understanding the role of these unforced errors “could provide comfort to the millions of patients who developed cancer but led near-perfect [healthy] lifestyles,” said cancer biologist Dr. Bert Vogelstein of Johns Hopkins University, senior author of both the original study and the new one. “This is particularly true for parents of children who have cancer” and might blame the tragedy on the genes they passed on to their child or the environment they provided, he said.

However they acknowledge that there is more to it than that. The article is an additional 11 paragraphs (hit the link above to read it!), two of which I excerpt below.

…There is a difference between how cancer-causing mutations come about and whether that cancer is preventable, they acknowledge. For instance, 65 percent of mutations in lung cancers arose randomly but 89 percent of those cancers are preventable by avoiding smoking, Tomasetti said.

Their critics argue that the environment’s effect on cancer goes beyond mutations, in which case prevention might have an even bigger role to play. Whether a few malignant cells form a dangerous tumor depends on, among other things, levels of inflammation, insulin, and obesity. Those influences don’t show up in genomic analyses like those the Hopkins researchers did but are affected by lifestyle and environmental factors, said Ross Prentice, a renowned cancer biostatistician at Fred Hutchinson Cancer Center in Seattle.