Monday, August 14, 2017

Can 40 percent of cancers be prevented?

Vast majority of cancer-causing mutations due to random DNA errors, new study indicates

"Two-thirds of cancer mutations are due to random DNA copying errors, study says."

That's the bulk of a slightly scary headline at the top of a recent "To Your Health" section of The Washington Post website.

In a story by Laurie McKinley, the study — published in "Science" magazine — cancer-causing mutations occur when normal cells divide. 

Humans, according to the piece, "have trillions of cells, which are constantly regenerating by dividing and making new cells. But each time DNA is copied, the scientists said, an average of three random mistakes will occur. While most are harmless, a small number affect genes that will promote cancer."

Bert Vogelstein
The Post article indicates that two Johns Hopkins University researchers — Bert Vogelstein, a cancer geneticist, and Cristian Tomaetti, a mathematician — were able in their study to separate the randomness factor from the other main contributors to cancer: inherited genes and environmental factors such as smoking and obesity.

Cristian Tomasetti
Results, after analyzing  "genome sequencing and epidemiological data for 32 types of cancer," assigned the mutations thusly: 66 percent, DNA-replication mistakes; 29 percent, environmental factors; 5 percent, heredity.

Variations depended on what kind of cancer they were talking about. According to the story, for example, "random DNA-replication mistakes account for about 77 percent of critical mutations in pancreatic cancer, and virtually all childhood cancer."

But "more than two-thirds of the mutations in lung cancer were due to environmental factors, mostly smoking."

McGinley's piece noted that "the new research builds on a 2015 study that highlighted the role of 'bad luck' — random DNA errors — in developing cancer. That study drew vehement protests from some cancer physicians and researchers who worried it would encourage people to take a fatalistic approach to cancer rather than trying to reduce their cancer risk by maintaining a healthy weight, exercising regularly, eating a good diet and avoiding cigarettes."

The Hopkins researchers have claimed "their earlier work was widely misinterpreted," the article continued — and emphasized that the new study "was consistent with estimates that 40 percent of cancers can be prevented."

Vogelstein insisted said that "science needs to find better ways to detect cancer early, when there is a good chance of curing it."

According to the story, critics of the 2015 study "disliked the 'bad luck' explanation and complained that the study was limited to the United States and didn't include the most common cancers — breast and prostate."

Insights into cancer mutations — especially BRCA1 and BRCA2 genes — can be found in "Rollercoaster: How a man can survive his partner's breast cancer," a VitalityPress book I, Woody Weingarten, aimed at male caregivers.

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