Update From the Medical Journals: January 2011 - What Your Doctor Is Reading - Harvard Commentaries

What's the latest news in the medical journals this month? Find out what your doctor is reading.

Anti-Estrogen Drug May Improve Lung Cancer Survival
Antibiotics May Help Some People with Irritable Bowel Syndrome
New Brain Scan May Diagnose Alzheimer's Disease
More News in Brief: Brain Hemorrhage Patients Should Avoid Statin Drugs; Depression Medicine May Help Stroke Recovery; Adults Age 60 and Older Should Get Shingles Vaccine

We don't have good treatments for lung cancer. The only exception is surgery for lung cancer that is caught early. But a new study suggests that a breast cancer drug may give us an invaluable new way to fight lung cancer. This study was released online by Cancer on January 24.

According to the Geneva Cancer Registry, breast cancer affected 6,655 women in Switzerland during a 23-year period covered by the registry. Forty of these women also developed lung cancer.

Researchers looked at the medical histories of these women. They wanted to see if lung cancer survival was affected by breast cancer treatment. What they found was very exciting.

About half of the women who had both cancers had been treated with the drug tamoxifen. (Tamoxifen blocks the effects of the hormone estrogen.) These women were 87% less likely to die from lung cancer than women who didn't get tamoxifen for their breast cancer.

We know from previous research that there are estrogen and progesterone receptors on the surface of lung cancer cells in a fairly large number of lung cancer patients. Tamoxifen is an anti-estrogen drug. It's common for women being treated for breast cancer to take this drug for five years. The strong association between tamoxifen and lung cancer survival suggests that estrogen may stimulate some lung cancers to grow. This would explain why tamoxifen use was linked with better survival.

More studies are needed to confirm this benefit. But it's likely that lung cancer patients and their doctors will begin using this treatment without waiting for more studies. The risks from tamoxifen treatment are fairly small, and the drug may be life-saving.

On January 6 the New England Journal of Medicine published two studies that appeared to promote antibiotics to treat irritable bowel syndrome (IBS). The studies, however, were disappointing.

The researchers credited the antibiotic treatment with improving symptoms for about 1 out of 10 people with IBS who had previously had frequent diarrhea. It was not clear from this study whether the benefit would last longer than a few months. The study did not look at people who had IBS with constipation but no diarrhea. They are not expected to benefit from antibiotics.

The studies included 1,260 patients. Half of the people received rifaximin (Xifaxan), an antibiotic that is used to treat travelers diarrhea and bacterial overgrowth in the intestine. The other half received placebo pills. The treatment lasted two weeks.

Forty-one percent of people who took the antibiotic had "adequate" clearing of symptoms. This number is not much higher than what the placebo group experienced: 32% reported complete or "adequate" relief of pain, bloating and diarrhea symptoms for at least 2 out of the first 4 weeks in the study.

Bloating symptoms improved in 30% of placebo patients and 40% of patients in the rifaximin group. In general, improvement could only be attributed to the drug in 9% to 10% of patients due to the high rate of improvement in the placebo group.

A subset of patients with IBS may have symptoms related to overgrowth of bacteria, or in some way may be sensitive to bacteria in the gut. But it's not clear that antibiotic treatment provides enough of a benefit to be worth the risks.

Based on this study, we don't know how long the benefits from rifaximin will last. Experts are already worried that this study could lead to the widespread use of the antibiotic, perhaps even repeated courses of treatment in the same individuals. Overuse of antibiotics leads to the development of multi-drug resistant bacteria, which is a dangerous problem.

A new way of scanning the brain may allow us to more accurately diagnose Alzheimer's disease, according to a study published January 19 in the Journal of the American Medical Association (JAMA).

We know from autopsy studies that brain deposits of a protein known as beta-amyloid are a hallmark of Alzheimer's disease. But they can't usually be seen on a brain scan. This study looked at an experimental imaging chemical, florbetapir, that binds to beta-amyloid deposits. Florbetapir is mildly radioactive so it can be seen on a positron emission tomography (PET) scan. A PET scan combines several imaging techniques — computed tomography (CT) scan, nuclear (radioactivity) detection tests and three-dimensional model construction by a computer. PET scans are also one of our most expensive medical tests.

In the study, 29 elderly people (some with and some without Alzheimer's) and 74 younger adults got a PET scan. Researchers had to wait until all of the elderly people had died and had autopsies to analyze the results. The elderly people's scans matched reasonably well with the autopsy results — 15 out of the 29 elderly people had Alzheimer's disease that was confirmed by autopsy, and the test and autopsy results agreed for 28 out of 29 people. None of the 74 healthy young people had positive scans.

The U.S. Food and Drug Administration (FDA) has not yet approved florbetapir for use outside of research studies. It is considering safety data and considering the usefulness of the test. The FDA is concerned about false positive and false negative readings. That's because the people reading the scans sometimes had different opinions about what they saw before a scan was considered positive or negative for Alzheimer's disease.

It's likely that there will be more variation (and more wrong diagnoses) if florbetapir is approved for use by doctors. With such a small study, we are not able to say whether there are conditions other than Alzheimer's disease that might give a positive result (potentially, giving a false positive diagnosis for Alzheimer's).

Even if the test is accurate, doctors are unsure if the cost can be justified. Currently, a PET scan usually costs several thousand dollars. We don't yet have very effective ways of treating Alzheimer's disease, so early diagnosis might not substantially improve care.

However, this new scan may make research easier. If Alzheimer's can be accurately diagnosed in early stages, and the progress of the disease can be monitored by a scan, it will be easier to study new drugs that might treat the disease.

Brain Hemorrhage Patients Should Avoid Statin Drugs. Cholesterol is a normal part of cell membranes; it's particularly important to nerve cells in the brain. But too much cholesterol is bad for our arteries. Some people take a statin drug to help lower cholesterol. A new study published online in the Archives of Neurology on January 10 was designed to weigh the risks and benefits of statins among people who had a previous stroke, particularly if the stroke involved bleeding. Based on a previous study, stroke patients who were taking statins at the time of their stroke had slightly higher rates of bleeding into the brain. Experts concluded that statins might be to blame for this. People who had had a previous brain hemorrhage as part of a stroke are at high risk for another brain bleed. The researchers used a computer model to predict how well statins would prevent heart attacks and other heart and blood vessel events, but also if the drugs would increasae the risk for another brain bleed. The results showed that patients who had "lobar" brain hemorrhages (hemorrhages into the frontal, temporal, or occipital lobes of the brain) would have a 22% chance of having a repeat brain hemorrhage if statin treatment was used after hemorrhagic stroke. Without statins, there was a 14% chance of recurrent hemorrhage. For people who had bleeding into the brainstem, thalamus or other deep brain structures, the risks and benefits were about equal. This analysis suggests that people who have ever had brain hemorrhage as a feature of stroke should avoided taking statins. They can be more harmful than beneficial in this group of people. This computer model did not make predictions or recommendations for people who have had stroke without hemorrhage.

Depression Medicine May Help Stroke Recovery. In the first 3 months after a stroke, a common pill given for depression may help you to recover body movement. This was revealed January 9 in a study that was published online by Neurology. Researchers treated people with fluoxetine (Prozac) after a stroke. They chose 118 people for their study whose stroke had caused weakness or paralysis. Treatment began 5 to 10 days after the stroke. Half were treated with fluoxetine for 3 months. The others got placebo pills. Both groups did physical therapy. People who got fluoxetine had a modest improvement in arm and leg strength compared with people who got the placebo. Three months after the stroke, more people in the fluoxetine group were living outside of a nursing home. These results were similar to findings of a study from a year ago when researchers reported that escitalopram (Lexapro) after a stroke helped people to recover thinking, learning, memory and verbal skills. Lexapro and Prozac are very similar antidepressants. They both boost activity of the brain hormone serotonin. Researchers think these medicines stimulate brain chemistry after a stroke. This may allow more chemical and electrical connections to form between cells. Studies about antidepressant use after stroke have been very small. This treatment can be recommended to patients who have had a stroke, with the understanding that these findings are preliminary. We still need larger studies.

Adults Age 60 and Older Should Get Shingles Vaccine. Encouraged by a new shingles vaccine study, the U.S. Centers for Disease Control and Prevention (CDC) has repeated its existing recommendation for adults age 60 and older to get vaccinated against shingles. The study was released January 12 in the Journal of the American Medical Association (JAMA). (For more information about the CDC's recommendation, go to its website.) The study tracked 300,000 patients in the Kaiser Permanente Southern California health plan. These were the first data to come from real-life use of the vaccine. They showed that the vaccine reduced the risk of shingles by 51%. It also reduced the risk for the painful nerve complication of shingles known as post-herpetic neuralgia by 67% compared with unvaccinated people. The recommendation is the same whether or not you remember having chicken pox as a child, and whether or not you have previously had an episode of shingles. Many insurance plans require that patients pay $100 or more towards the cost of the vaccine, and this has led to the vaccination being less popular than predicted.

Mary Pickett, M.D. is an Associate professor at Oregon Health & Science University where she is a primary care doctor for adults. She supervises and educates residents in the field of Internal Medicine, for outpatient and hospital care. She is a Lecturer for Harvard Medical School and a Senior Medical Editor for Harvard Health Publications.

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