Environment
The cancer study bombshell that wasn’t
Were the New York Times and the Washington Post writing about the same New England Journal of Medicine article?
Medical quiz du jour: A study published Thursday in the New England Journal of Medicine revealed that A) genes are more important than we thought in causing cancer, or B) genes are less important than we thought in causing cancer.
Correct answer: C) more important if you read The New York Times, less important if you read the Washington Post.
According to the lead of the Post’s front-page report on the study, “The vast majority of cancers are caused not by inherited defects in people’s genes, as many have come to believe in this age of genetics, but by environmental and behavioral factors.”
The Times covered the study with an AP dispatch on page A-21: “Genes may cause more than one-quarter of three major types of cancer, more than previously thought, a group of researchers says.”
The reason for this confusion is simple. The New England Journal article, which is based on a large study of twins, essentially tells us what we already knew: that genes and environment both play a role in cancer, just as they play roles in everything else human.
While the article is based on the impressive number-crunching of the medical records of 44,788 pairs of Scandinavian twins, it doesn’t contain any major revelations. More than anything, it points to the fact that twin studies, which have long amazed some people and angered others, may be on the verge of outliving their usefulness.
Even though the authors examined the records of a total of 10,803 people with cancer, they got statistically relevant data on only four types of cancer — breast, colorectal, lung and prostate. Even here the authors acknowledge margins of error of up to 50 percent. The study also lacks data on specific types of environmental exposures that may have contributed to the cancers.
“The study has many strengths but its weaknesses illustrate the difficulties of using data on twins in studies of cancer,” Dr. Robert Hoover, director of epidemiology and biostatistics at the National Cancer Institute, writes in an editorial accompanying the study.
“Delineation of the specific environmental and genetic components of the risk of cancer,” he adds, “is likely to depend on the emerging new generation of large molecular epidemiological studies, rather than on studies of twins.”
The basic idea of twin studies is to gather data on large numbers of fraternal and identical twin pairs and then compare the similarities of the two sets for things like cancer, asthma, schizophrenia and left-handedness.
Identical twins share all of their genes, while fraternal twins are no more identical, genetically, than other siblings, which means they share an average of 50 percent of their DNA.
Twin studies that try to assess the genetic component to things like intelligence and aggression have been a political hot potato, for obvious reasons. But the scientists who conduct them all agree that genes and environment both play a role in behavior, so there isn’t really much controversy left.
In the Scandinavian study, the researchers found that 40 of 299 sets of fraternal twins both suffered prostate cancer, while only 20 of the 584 fraternal twins both got the disease.
The Journal’s authors, led by Dr. Paul Lichtenstein of the Karolinska Institute in Stockholm, Sweden, cranked those figures through a statistical analysis and came up with the estimate that 42 percent of the risk for prostate cancer comes from heritable factors. Using the same type of analysis, they found that 35 percent of the risk for colorectal cancer and 27 percent of breast cancer risk came from genes.
These numbers mean that the identical twin of someone with prostate, colorectal or breast cancer has an 11, 13 or 18 percent chance, respectively, of getting the same disease. Which means genes are significant to these diseases, but not determinant.
What this tells you is that the Post lead is actually closer to the truth. “The fatalism of the general public about the inevitability of genetic effects,” as the study’s authors write, “should be easily dispelled” by the data here.
But we didn’t really need a twin study to tell us that. Plenty of studies of cancer have shown a significant genetic component.
Still, even if identical twins are no longer needed to prove that genes are involved in various diseases and traits, they can still make a contribution to science — through the study of their differences.
For example, identical twin sets in which one twin gets breast cancer and the other doesn’t offer researchers a chance to figure out the environmental triggers for cancer, by examining the different environmental exposures of the two twins.
“Whether you view genes or environment as more important tends to grow out of your own life experiences,” says Nancy L. Segal, a Cal State-Fullerton psychologist who studies twins. “But I think in the future, we’re going to see more studies of discordant twins.”
Arthur Allen writes on health, science and other issues for Salon. He lives in Washington. More Arthur Allen.
Romney flips on coal
The GOP nominee attacked Obama over coal on Tuesday, but he once wanted greater regulation
Mitt Romney in Craig, Colo., on Tuesday. (Credit: AP) Mitt Romney’s campaign swung through the coal town of Craig, Colorado, today so that the candidate could slam President Obama for supposedly killing the coal industry, even though Romney pursued his own regulations against coal companies as governor of Massachusetts.
“He’s going after energy. He’s made it harder to get coal out of the ground,” Romney said. “I’m not going to forget communities like this across the country that are hurting right now under this president.”
Continue Reading CloseAlex Seitz-Wald is Salon's political reporter. Email him at aseitz-wald@salon.com, and follow him on Twitter @aseitzwald. More Alex Seitz-Wald.
Farmers’ sand-frac nightmare
Some parts of rural America are being ruined by an unstoppable new mining industry -- and it's spreading
Frac sand piles up at a processing plant in Chippewa Falls, Wis. (Credit: AP/Steve Karnowski) If the world can be seen in a grain of sand, watch out. As Wisconsinites are learning, there’s money (and misery) in sand — and if you’ve got the right kind, an oil company may soon be at your doorstep.
March in Wisconsin used to mean snow on the ground, temperatures so cold that farmers worried about their cows freezing to death. But as I traveled around rural townships and villages in early March to interview people about frac-sand mining, a little-known cousin of hydraulic fracturing or “fracking,” daytime temperatures soared to nearly 80 degrees — bizarre weather that seemed to be sending a meteorological message.
Continue Reading CloseWorse than Keystone
Environmentalists are focused oil and gas, but a bigger carbon disaster may be brewing in the Pacific Northwest
A coal mine owned by Arch Coal Co. (Credit: AP/Matthew Brown) Coal is without question our dirtiest fuel source: When burned, it dumps toxins like mercury and nitrogen oxides into the air and packs an outsize punch when it comes to carbon emissions. Since America has a lot of it, though, we’ve tended to use a lot: Historically, around half our electricity has been generated by coal combustion plants. But as a result of sustained anti-coal activism, low prices for natural gas, and new EPA regulations on power plant emissions, Americans are using a lot less coal than we used to, and the future of the sooty stuff in this country is looking dim. So the U.S. coal industry is pinning its hopes on China. While historically most of our exported coal has gone to Europe, U.S. exports to China increased 176 percent between 2009 and 2010, and that number is likely to keep rising as the Asian market for coal continues to expand. The prospect of shipping coal across the Pacific is even more appealing considering that Western states like Wyoming and Montana have vast coal reserves in the Powder River Basin, one of the largest coal deposits in the world.
Continue Reading CloseAlyssa Battistoni writes about the environment and politics from Seattle. More Alyssa Battistoni.
Is it ethical to drive stick?
More drivers are buying manual transmissions -- a boon for auto sentimentalists but bad news for the environment
(Credit: cristapper via Shutterstock) Ever since I first watched my dad drive his chocolate brown Datsun 280 ZX back in the early 1980s, I’ve been inculcated to believe that driving — true driving — can only be performed with a stick shift. From that childhood experience, I came to see the manual transmission as a birthright passed down from my grandfather, to my father, and eventually to me via a series of tense, stall-filled lessons when I turned 16. In my case, after ripping apart the transmission one too many times, my dad went barking drill sergeant on me, eventually teaching me that a stick requires a special kind of focus, and that I needed to ease up more slowly on the clutch in order to get into first gear on those damn inclines. Through the experience, I learned to consider my stick-shifting skill a special talent with transcendent value.
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David Sirota is a best-selling author of the new book "Back to Our Future: How the 1980s Explain the World We Live In Now." He hosts the morning show on AM760 in Colorado. E-mail him at ds@davidsirota.com, follow him on Twitter @davidsirota or visit his website at www.davidsirota.com. More David Sirota.
An eco-pioneer’s final words
The visionary author of "Ecotopia," who died in April, warns of dark times ahead, but sees a path through the decay
To all brothers and sisters who hold the dream in their hearts of a future world in which humans and all other beings live in harmony and mutual support — a world of sustainability, stability, and confidence. A world something like the one I described, so long ago, in “Ecotopia” and “Ecotopia Emerging.”
As I survey my life, which is coming near its end, I want to set down a few thoughts that might be useful to those coming after. It will soon be time for me to give back to Gaia the nutrients that I have used during a long, busy and happy life. I am not bitter or resentful at the approaching end; I have been one of the extraordinarily lucky ones. So it behooves me here to gather together some thoughts and attitudes that may prove useful in the dark times we are facing: a century or more of exceedingly difficult times.
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