Advanced breast cancer has increased slightly among young women, a 34-year analysis suggests. The disease is still uncommon among women younger than 40, and the small change has experts scratching their heads about possible reasons.

The results are potentially worrisome because young women's tumors tend to be more aggressive than older women's, and they're much less likely to get routine screening.

Still, that doesn't explain why there would be an increase in advanced cases and the researchers and other experts say more work is needed.

It's likely that the increase has more than one cause, said lead author Dr. Rebecca Johnson, medical director of a teen and young adult cancer program at Seattle Children's Hospital.

"The change might be due to some sort of modifiable risk factor, like a lifestyle change" or exposure to some sort of cancer-linked substance, she said.

Johnson said the results translate to about 250 advanced cases diagnosed in women younger than 40 in the mid-1970s vs. more than 800 in 2009. During those years, the number of women nationwide in that age range went from about 22 million to closer to 30 million — an increase that explains part of the study trend "but definitely not all of it," Johnson said.

Other experts said women delaying pregnancy might be a factor, partly because getting pregnant at an older age might cause an already growing tumor to spread more quickly in response to pregnancy hormones.

The study was published in the Journal of the American Medical Association.

Sugar has strong diabetes link

A worldwide analysis shows that regardless of its effect on obesity, the ebb and flow of sugar in a country's diet strongly influences the diabetes rate.

The new study provides compelling evidence that obesity isn't driving the worldwide pandemic of Type 2 diabetes as much as the rising consumption of sugar — largely in the form of sweetened sodas, experts said.

Increases in sugar intake account for a third of new cases of diabetes in the United States and a quarter of cases worldwide, according to calculations published in the journal PLOS ONE. In the 175 countries studied, a 150-calorie daily increase in the availability of sugar — about the equivalent of a can of Coke or Pepsi — raises the prevalence of Type 2 diabetes by 1.1 percent, a research team from Stanford University and the University of California, San Francisco, found.

The results make clear that sugar consumption "is fueling the global epidemic of diabetes," said Dr. Walter Willett, an epidemiologist at the Harvard School of Public Health who was not involved in the study.

In a statement, the Sugar Association faulted the study for failing to separate the effects of "natural sugar" and high-fructose corn syrup.

sleep deprivation leads to other ills

Just a week of inadequate sleep can alter the activity of hundreds of genes, which may help scientists explain how wakeful nights can lead to such ailments as diabetes, obesity and heart disease.

Blood samples taken from patients revealed genetic changes that, with further research, may help answer why sleepless nights are so harmful to health, according to the study published in the Proceedings of the National Academy of Sciences. While not all of the altered genes have known functions, some are involved in metabolism and stress response.

More than one-third of Americans sleep fewer than seven hours a night, affecting their ability to concentrate, according to the U.S. Centers for Disease Control and Prevention.

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