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Fri 31 Oct 2008 04:00 AM

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Science says

A report back on the latest medical and scientific studies from around the world.

A report back on the latest medical and scientific studies from around the world.

Cancer

Powerful, tiny test detects tumours & suggests best treatment

Massachusetts General Hospital researchers have developed a powerful test that can identify tiny amounts of tumour cells floating in the blood of cancer patients.

Already, the technology, known as the CTC-chip, has accurately identified bloodstream cancer cells in patients with advanced cancer of the lung, prostate, pancreas, breast, or colon.

Although the device is not yet ready for widespread use, the New England Journal of Medicine reports that it successfully identified migrating cancer cells in lung cancer patients and spotted important genetic quirks in those cells. The innovation could revolutionise treatment, especially for lung cancer.

The technology uses a scanner the size of a business card to analyse a patient's blood and can detect a single cancer cell among 1 billion healthy blood cells. Once those cells are captured, their genetic fingerprints can help determine the most effective drug for a patient whose cancer has already begun spreading, and show whether medication is still effective.

The test is now being used on patients whose cancer has already spread, but scientists hope in future the chip will be able to detect cancer's spread before secondary tumours become established.

The tiny device has 78 000 posts imbedded inside to trap cancer cells. Each of those posts is coated with a substance that acts like glue - glue designed to stick only to circulating tumour cells, known by the acronym CTC.

Already, the technology, known as the CTC-chip, has accurately identified bloodstream cancer cells in patients with advanced cancer of the lung, prostate, pancreas, breast, or colon.

Dr Daniel Haber, director of the Mass. General Hospital Cancer Center and senior study author says, "It's like a pinball machine - the blood has to flow through all of these columns to get to the other side. All the normal blood cells flow right through, but the very, very rare cancer cells stick to the columns."

The focus of the new study was on non-small-cell lung cancer. When the Mass. General team took blood from 27 lung cancer patients, the chip technology accurately detected circulating tumour cells in each patient.

And then they looked for crucial genetic mutations that would suggest particular treatments. By confirming with biopsied tissue, the scientists found that their test detected all the important genetic features they had sought.

The Mass. General technology needs to be tested in larger groups of patients before it can be used routinely, and scientists would like to speed up the device's ability to process samples - right now, it takes about 8 hours to run a blood sample and analyse it.

Source: Massachussetts General Hospital, July 2008, www.mgh.harvard.edu

Diabetes

High level of fetuin-A equals high risk for diabetes

According to a new study, having a higher than normal level of fetuin-A in the blood is linked to an increased risk for the development of diabetes.

The study's authors write: "Type 2 diabetes mellitus has become a global epidemic and the increased prevalence of obesity is a major contributing factor. However, diabetes does not develop in all obese individuals and there is a strong genetic contribution to risk. Despite significant recent advances, mechanisms responsible for individual differences in clinical phenotype remain largely unknown."

Previous studies have found a link between higher fetuin-A levels and insulin resistance, but the link with type 2 diabetes mellitus is unknown.

Dr Joachim Ix, of the University of California, San Diego, and colleagues conducted a study to examine whether higher fetuin-A levels are linked to occurrence of diabetes. The study included 406 people without diabetes at the start of the study, whose fetuin-A levels had been measured at baseline, and who had 6 years of follow-up. Diabetes developed in 135 cases.

Analysis showed a gradual increase in the incidence of diabetes with increased fetuin-A levels.

The group with the highest levels had more than double the incidence rate than the lowest third. The link was independent of patients' level of exercise, inflammatory biomarkers, and other commonly available measures of insulin resistance.

The study's authors conclude: "Future studies should evaluate whether the results may generalise to middle-aged individuals in whom the [diabetes] incidence rate is highest. If confirmed in future studies, fetuin-A may ultimately prove useful as a target for therapeutics, and its study may provide novel insights to glucose metabolism in humans."

Source: JAMA, 2008;300[2]:182-188, July 2008, http://pubs.ama-assn.org/media/2008j/0708.dtl#2 Heart disease

Heparin linked to high risk of bleeding post cardio embolic stroke

Administering heparin soon after cardio embolic stroke is linked to an increased risk for serious bleeding, according to a new study. But it also reports that anticoagulation with warfarin therapy may safely begin shortly after stroke.

Patients receiving only aspirin therapy were 12.5 times more likely to experience stroke progression than patients who received other anticoagulation therapies.

Current guidelines don't recommend giving anticoagulation therapy to patients shortly after cardio embolic stroke. But most patients who have this type of stroke eventually need it and there is no consensus regarding the best way to begin treatment.

Dr Hen Hallevi and colleagues from the University of Texas Health Science Center at Houston, studied 204 patients who had been admitted with cardio embolic stroke between 2004 and 2006.

Of these, 8 received no anti-clotting therapy; 88 received aspirin only; 35 were given aspirin and warfarin; 44 received intravenous heparin and warfarin; and 29 were treated with a full dose of enoxaparin, a low-molecular-weight-heparin, followed by warfarin. All patients who did not receive full doses of heparin or enoxaparin took low doses of enoxaparin to prevent deep vein thrombosis.

Recurrent strokes occurred in 2 patients (1%). The most common serious adverse event was a progressive stroke, seen in 11 patients (5%). All except 1 of these cases occurred in the aspirin-only group.

Patients receiving only aspirin therapy were 12.5 times more likely to experience stroke progression than patients who received other anticoagulation therapies, and patients with progressive strokes were 18 times more likely to have a poor outcome.

Haemorrhagic transformation was observed in 23 cases (11%) but only 3 (1%) were symptomatic. All 3 of these cases occurred in patients taking full-dose enoxaparin. Systemic bleeding occurred in 2 patients (1%), both taking heparin.

The authors write: "Warfarin treatment appears to be safe and can be started at any point during the hospital stay along with deep vein thrombosis prophylaxis. Bridging with a full dose of enoxaparin or heparin may carry a high risk of intracranial and systemic bleeding. However, it may be considered in special circumstances."

Source: JAMA, July 2008, Archives of Neurology, September 2008, http://pubs.ama-assn.org/media/2008a/0714.dtl#7

DiabetesLaser better than steroids for diabetic macular oedema

A study funded by the National Eye Institute (NEI) in the US shows that laser therapy is not only more effective than corticosteroids in the long-term treatment of diabetic macular oedema, but also has far fewer side effects.

Around 5 years ago, early reports of success in treating diabetic macular oedema with injections of a corticosteroid called triamcinolone led to the rise in popularity of this type of treatment. This is the first study to compare the long-term benefits of both treatments and their potential side effects.

"Results of this study should confirm the use of laser treatment for diabetic macular oedema and will have a significant impact on quality of life for tens of thousands of people being treated for diabetic macular oedema in the United States each year," according to Dr Paul Sieving, director of the NEI.

693 patients with diabetic macular oedema participated in the study at 88 sites across the US. Each patient was randomly assigned to corticosteroid or traditional laser treatment. In the corticosteroid-treated group, 28% experienced substantial vision loss as compared to 19% in the laser-treated group. Additionally, about a third of the eyes treated with laser therapy showed substantial improvement in vision.

Dr Michael Ip, associate professor of ophthalmology at the University of Wisconsin, and chair of the protocol for the Diabetic Retinopathy Clinical Research Network (DRCR.net) says, "Many of the investigators were surprised by the results. These findings substantiate the importance of laser treatment in the management of diabetic macular oedema."

The corticosteroid-treated group was also far more likely to experience side effects. 51% had cataract surgery vs. 13% of those in the laser-treated group. In addition, almost half of the corticosteroid-treated group had increased eye pressure and a third needed medication to lower it. The laser-treated group had far less of a problem with eye pressure. Source: PNAS, July 2008, Ophthalmology, www.nih.gov/news/health/jul2008/nei-28.htm

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