Eating fish tied to lower risk of colon polyps

NEW YORK (Reuters Health) - Women who eat about three servings of fish per week have a somewhat lower chance of having polyps found during a routine colonoscopy than women who eat just one serving every two weeks, according to a new study.

The research doesn't prove that seafood protects against polyps, but it "does increase our confidence that something real is going on," said Dr. Edward Giovannucci, a professor at the Harvard School of Public Health in Boston, who was not involved in this study.

A polyp, also called an adenoma, is a mushroom-shaped tag of tissue that grows in the colon and can develop into colorectal cancer.

The idea researchers have been pursuing is that the omega-3 fats in fish might have an anti-inflammatory effect, similar to aspirin, that could prevent the development of polyps.

Giovannucci said that earlier experiments in animals have showed that omega-3 fats can reduce the risk of this cancer, but that studies of humans have had mixed results.

In the latest study, the researchers surveyed more than 5,300 people about their eating habits. All of the participants had come in to the researchers' practices for a colonoscopy.

The team then compared more than 1,400 women without polyps to 456 who had adenomas detected during the procedure.

Among women with adenomas, 23 percent were in the bottom fifth among fish eaters, while 15 percent were in the top fifth. That means people who eat lots of seafood are somehow protected against polyps, because otherwise the percentages should have been the same.

After accounting for differences like age, smoking and aspirin use, women who ate the most fish -- three servings a week -- were 33 percent less likely to have a polyp detected than those who ate the least -- less than a serving a week.

Of course, it's never possible to rule out that other factors could explain the findings. For instance, it's possible that fish lovers have other healthy behaviors that decrease their risk of polyps.

What's more, the study didn't follow the women to see whether either group was more likely to go on to develop cancer. But Dr. Harvey Murff, the lead author of the study and a professor at Vanderbilt University in Nashville, Tennessee, said polyps are a reliable predictor for cancer risk.

"Adenomas are generally believed to be the precursor" to cancer, Murff told Reuters Health. "You would think most things that would reduce adenoma risk would subsequently reduce cancer risk."

A 33 percent lower risk is not enormous, but Giovannucci said "it is important because colorectal cancer is a common cancer." About 140,000 new cases of colon and rectal cancer are diagnosed each year in the United States, and more than 50,000 people will die from the cancer. The lifetime risk of developing the disease is about 20 percent, according to the American Cancer Society.

The men in Murff's study who ate a lot of fish did not see the same reductions in polyp risk as women, however.

Murff said he doesn't have a good explanation for that, but perhaps men are less sensitive to the omega-3s in fish and need to eat more to get any benefit. It could also be that men might eat more omega-6 fats, counteracting the effects of the omega-3s.

Omega-6 fatty acids are related to the production of a hormone called prostaglandin E2, which is associated with inflammation.

Murff explained that eating omega-3 fatty acids tamps down the body's levels of omega-6 fatty acids. In turn, the body then has reduced levels of prostaglandin E2.

He and his colleagues demonstrated this by showing that the women in the study who ate more fish -- and presumably, more omega-3s -- had lower levels of prostaglandin E2.

"We know people who have higher levels of this (hormone) are more likely to develop colorectal cancer. So in essence, by eating more omega-3 fatty acids, it's almost like taking an anti-inflammatory medication," Murff told Reuters Health.

There is still more work to be done to prove that the omega-3 fatty acids are actually the reason for the reduced colorectal cancer risk.

But, Giovannucci said, "I think this (association) has a pretty strong biologic rationale."

SOURCE: http://bit.ly/zWMCyQ The American Journal of Clinical Nutrition.

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Diabetes drugs tied to pancreatic cancer risk

NEW YORK (Reuters Health) - A new study links the diabetes drug metformin to fewer cases of pancreatic cancer -- at least in women -- but finds other diabetes medications are associated with a higher risk of the disease.

The differences in medication history among people who did or didn't get pancreatic cancer were small, researchers said, and it's unclear why the drugs might affect cancer risks in men and women differently.

Still, the new finding is in line with previous research suggesting that metformin may decrease the risk of multiple cancers, said Dr. Peter Butler, a diabetes researcher at the University of California, Los Angeles David Geffen School of Medicine, who wasn't involved in the new study.

"One theme that seems to be coming through... is that the oldest drug we have for diabetes, metformin, is undoubtedly the best drug we have for diabetes," he told Reuters Health.

Pancreatic cancer is relatively rare as far as cancers go, but progresses quickly; most people don't survive more than a couple years after diagnosis. The National Cancer Institute estimates that about 44,000 people will be diagnosed with pancreatic cancer in the United States this year, and close to 38,000 will die from the disease.

Research has suggested that people with pancreatic cancer may have an increased risk of diabetes, but it's unclear how diabetes -- and the drugs used to treat it -- may affect pancreatic cancer risks in previously cancer-free people.

To help answer that question, Dr. Christoph Meier of the University Hospital Basel in Switzerland and his colleagues consulted a database of more than eight million people in the UK, including about 2,800 who were diagnosed with pancreatic cancer between 1995 and 2009.

For each of those people, they found another six of the same age and gender that didn't have pancreatic cancer to serve as a comparison group.

Using records from primary care doctors, the researchers determined how many people in the pancreatic cancer and cancer-free groups had previously been diagnosed with diabetes and were on an anti-diabetes drug, such as metformin or sulfonylureas, which include glimepiride and glyburide.

Those drugs cause the body to make or absorb less glucose (metformin) or to produce more insulin (sulfonylureas) to keep blood sugar levels in check.

One in nine people with pancreatic cancer had a prior diagnosis of diabetes, compared to about one in twelve in the cancer-free comparison group, according to findings published Tuesday in the American Journal of Gastroenterology.

According to their medical records, two percent of people with pancreatic cancer had been taking metformin long-term before they were diagnosed, compared to 1.6 percent of the group without cancer -- a difference that could have been due to chance.

But when the researchers separated the records by gender, they found that significantly fewer women with a new diagnosis of pancreatic cancer had been taking metformin for at least a few years, compared to cancer-free women.

That was after the researchers had already taken into account whether women were overweight or obese and if they smoked or drank alcohol.

The association in one gender but not the other was "somewhat unexpected," according to Meier's team, and there's no clear biology-based way to explain why metformin might help protect women against pancreatic cancer, but not men.

The findings were reversed for insulin and sulfonylureas in the study population. Significantly more people with pancreatic cancer had a history of long-term use of those drugs than cancer-free people.

Craig Currie, who has studied diabetes drugs and cancer at the Cardiff University School of Medicine in the UK, said it makes sense that insulin and sulfonylureas would increase the risk of pancreatic cancer. Insulin promotes cancer growth, he said, and also acts directly on the pancreas.

The study's investigators "raise doubts about these treatments," he told Reuters Health in an email.

"There is a possibility that exogenous insulin (insulin that's not made naturally by the body) is of questionable safety in people with type 2 diabetes," added Currie, who didn't participate in the new research.

Still, absolute differences in medication use were small even in people with cancer: less than one percent of those with or without pancreatic cancer had taken insulin long-term. Sulfonylurea users accounted for just over three percent of people with a new pancreatic cancer diagnosis and two percent without cancer.

Butler said it's hard to tease out what cancer risks may be due to the drugs, and what could be a result of poor diet and lack of exercise, for example, in people with diabetes. He said that more research will be needed to tease out those specific effects.

"Honestly for patients at this point, I think this is another piece of the jigsaw puzzle," Butler said.

"This paper in itself would not cause me to recommend a change in treatment for people."

That said, Butler concluded that evidence suggests most people with type 2 diabetes who don't have any medical reasons not to take metformin should be on the drug, either alone or in combination with other anti-diabetes medications.

SOURCE: http://bit.ly/kkA6Tc American Journal of Gastroenterology, online.

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Second exam important in child sex-abuse cases

NEW YORK (Reuters Health) - When a child is thought to have been sexually abused, a second medical exam may be key to picking up injuries and sexually transmitted infections, a study published Monday finds.

The American Academy of Pediatrics already recommends that kids being examined for sexual assault have a follow-up exam in the weeks afterward.

But until now, no studies had looked at the benefits of doing that.

For the new report, researchers reviewed the records of 727 children and teenagers who were evaluated for sexual abuse or assault over a five-year period.

They found that almost one-quarter of the time, the patients' second exam changed the findings of the first.

In 18 percent of cases, there was a shift in the diagnosis of traumatic injuries.

Most often, the original examiner had said it was unclear whether the child had an injury suggestive of sexual assault (like tears or bruising), but the second examiner concluded that the findings were "normal."

However, that "does not in any way" mean the child wasn't sexually abused, said Dr. Nancy D. Kellogg, one of the researchers on the study and a child abuse expert at the University of Texas Health Science Center in San Antonio.

It's well known that sex-abuse victims often do not have telltale traumatic injuries, Kellogg told Reuters Health.

So it's what the child says that's most important.

Kellogg's team also found that the second medical exam helped pick up sexually transmitted diseases that weren't caught initially. That was true in nearly seven percent of cases.

Most often, Kellogg said, the follow-up exam caught genital warts -- which would not yet have been apparent during the first exam.

The findings, reported in the journal Pediatrics, are based on 727 children and teens who were first examined at one San Antonio ER or the regional child advocacy center. A doctor or nurse trained in child abuse cases performed the exams.

The second exam was done about a month later at the child advocacy center, by an experienced child-abuse doctor or nurse.

During the initial exam, Kellogg explained, kids are "anxious or in pain -- they're traumatized. And that can affect the examiner's ability to detect things."

But the researchers also found that the first examiner's experience mattered. If he or she had done fewer than 100 such exams, the second examiner was more likely to reach different conclusions on whether the child had a traumatic injury.

That, Kellogg said, points to the importance of having an experienced doctor or nurse do the second exam.

Some hospitals, she noted, have special "child abuse teams" who can evaluate kids for sexual assault. There may also be a nearby child advocacy center with doctors or nurses who can do the exam.

As for areas where those services aren't available, Kellogg said she hopes the current findings give less-experienced pediatricians some guidance in evaluating kids for sexual abuse.

"We were a bit surprised by the findings," she noted. "We didn't expect the follow-up exam to make such a big difference in so many kids."

SOURCE: http://bit.ly/A83tBr Pediatrics, online.

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