DNA betters Pap in detecting cervical cancer

WASHINGTON

The human papillomavirus (HVP) screening test for cervical cancer is far more accurate than the traditional Pap smear, according to a Canadian study published in the New England Journal of Medicine. The first round of the Canadian Cervical Cancer Screening Trial, led by Eduardo Franco, director of the division of cancer epidemiology at McGill's Faculty of Medicine, put the HPV test's accuracy in detecting precancerous lesions at 94.6 percent compared with 55.4 for the Pap.

    The trial, funded by a grant from the Canadian Institutes of Health Research, followed 10,154 women 30 to 69 years old in Montreal, Quebec, and St. John's, Newfoundland, from 2002 to 2005.

    "We already knew before conducting this study that the sensitivity of Pap left a lot to be desired," said Franco.

    The Pap smear, invented by Georgios Papanicolaou in the 1940s, requires technicians to look under a microscope for abnormalities in cell samples collected from the patient's cervix. It has been the standard screening procedure for cervical cancer for almost 50 years. The HPV test also requires the collection of cervical samples, but the analysis process is automated and detects the DNA of high-risk HPV strains known to cause cervical cancer.

    "Women currently vaccinated against cervical cancer will still need to be screened, because the vaccines that are available now only prevent about 70 percent of all cervical cancers, and they're primarily for young women," said Franco. "The HPV test may be ideal for vaccinated women once they reach screening age because it gives us an opportunity to monitor the protection that the vaccine is supposed to give them."

 

 

Nano breakthrough in cancer detection

PARIS

A nano-scale tool that distinguishes soft cancerous cells from stiffer normal ones could save lives by making it easier to diagnose cancer.

    Using atomic-force microscopes, a team of United States scientists showed for the first time that the surface of living cancer cells were more than 70 percent softer than their healthy counterparts. This measurable difference in elasticity held true across lung, breast, and pancreatic cancers, and could provide a powerful means of detecting malignant cells that might otherwise escape notice, said the study published in Nature Nanotechnology.

    Currently, pathologists examine surgically removed tissue by placing stained, thinly sliced sections on a glass slide and looking at them under a microscope for signs of the disease. Another type of test for differentiating cancerous and normal cells uses antibodies to pinpoint certain proteins.

    "However, this complex process of cancer diagnosis is not always 100-percent accurate because normal cells can sometimes look like cancerous cells," said Massachusetts Institute of Technology scientist Subra Suresh in an accompanying commentary.

    Earlier studies have shown that the frequency of diagnostic error for patients who have lung cancer may be as high as 15 percent due to sampling errors or faulty interpretation. Combining existing methods with the new technique, however, could help reduce this margin of error.

    In experiments conducted at the University of California in Los Angeles, a team of researchers led by James Gimzewski removed body fluid from suspected cancer patients. Using atomic-force microscopes-a nanotechnology gadget measured in units 10,000 times smaller than the width of a human hair-they applied minute amounts of pressure on individual cells with a sharp probe attached to a mechanical arm. The term "microscope" is, in fact, a misnomer because the tool gages surface pressure rather than providing a magnified view.

    The researchers discovered that malignant cells-verified as cancerous by other means-were four times as soft as normal tissue across all three types of cancer examined. "Our work shows that mechanical analysis can distinguish cancerous cells from normal ones even when they show similar shapes," Gimzewski and his colleagues concluded.

    When a normal cell becomes cancerous, its shape and its internal "skeleton" change. This transformation causes a loss of stiffness, but is not always visible. The softness, they noted, makes it easier for malignant cells to invade and spread to other parts of the body.

    Further tests are needed to see whether the simultaneous existence of other diseases besides cancer in a patient might affect the mechanical properties of the cells and thus throw off the nano-scale measurements.

 

 

Gullet cancer link seen with obesity

PARIS

Highly obese people are six times likelier to develop cancer of the gullet than people of healthy weight, according to a study published in the British journal Gut. The probe, carried out in Australia, looked at 793 people with esophageal cancer, who were compared with 1,580 counterparts matched for age and place of residence.

    Risks of developing this cancer were higher among individuals who had gastric acid reflux, which has long been associated with such tumors.

    But another big risk factor was obesity. Those with a body-mass index (BMI) of 40 or more were six times more at risk than people with a BMI of between 18.5 and 25, which is deemed to be a standard for good health.

    A combination of obesity and acid reflux boosted the risk by a factor of 16. The risk held true, even when smoking and high alcohol consumption, which are also culprits in cancer of the gullet, were taken into account.

    The paper speculates that obesity triggers an increase in levels of insulin and this in turn boosts the production of another hormone called insulin-like growth factor. These hormones are known to stimulate cell proliferation and inhibit apoptosis, conditions that favor cancer development.

    However, only further research will say whether this theory or rival hypotheses is right, say the authors, led by David Whiteman, a professor at the Queensland Institute of Medical Research in Brisbane.

 

 

Breast-cancer survival better after 40

SYDNEY

Women stand a better chance of surviving breast cancer if they are over 40 years old when diagnosed. An Australian study confirmed that survival rates are higher for women who detect the tumor early and for those with smaller tumors.

    Researchers from the Australian Institute of Health and Welfare and the National Breast Cancer Center looked at the survival rates of more than 10,000 women who were diagnosed with the disease in 1997. They found that the larger the cancer, the lower the chance of survival. Women whose cancers were 10 millimeters or less in diameter at diagnosis had a 98-percent chance of being alive five years later.

    "This declined to 73 percent for women with cancers 30 millimeters or more in diameter, and to 49 percent for women with advanced cancer where size had not been measured," said the institute's Christine Sturrock.

    Survival rates were higher if the cancer was detected before it spread to the lymph nodes while age was also a significant influence, with women under 40 having a lower survival rate, no matter what size the tumor. For these younger women, those with cancers 10 millimeters or less had a 95-percent survival rate while those whose growths had passed 30 millimeters had only a 67-percent chance of survival.

    The center's director, Dr Helen Zorbas, said the best outcomes appeared to be for those women diagnosed in their 50s. Women under 40 tend to have a lower survival rate than older women. "The tumors seem to behave differently in younger women," she said, adding that they tended to display larger and more aggressive tumors.

 

 

New target to battle breast cancer

CHICAGO

Researchers have identified a new target for drugs to help treat the most common form of breast cancer in the developing world. The target is a molecular "switch" in the protein-making machinery of the cancer cell that enables a tumor to aggressively develop its own blood supply.

    Women with locally advanced breast cancer can develop tumors that grow anywhere from two to 10 centimeters in diameter. The tumors are unusually large in many cases-they are often the size of a plum by the time they are diagnosed-due to the extremely dense network of blood vessels feeding them oxygen and nutrients.

    "Our study shows that an unusual molecular switch occurs that is essential for the development of these large tumors. We think that this switch could be a target for new therapies," said Robert Schneider, professor of molecular pathogenesis at New York University (NYU) School of Medicine.

    In a paper in Molecular Cell, Schneider and his colleagues describe how two proteins (4E-BP1 and eIF4G) which are present at elevated levels in locally advanced breast-cancer cells selectively increase the action of certain messenger, or mRNA, molecules. The effect of that process is to increase several fold the production of certain growth factors that drive tumor angiogenesis-the formation of the tumor's own blood vessels.

    "The switch gives us the ability to shut off production of growth factors in the tumor at their source," said Schneider. He said several experimental drugs are in development that would target the "switch," with a view to curbing its growth. If the drugs are shown to be successful in clinical trials, they could eventually be combined with a cocktail of chemotherapy drugs to eliminate the malignancy.

    "This research opens new avenues for the development of targeted approaches in the treatment of one of the most common lethal forms of breast cancer worldwide," said coauthor Silvia Formenti of the NYU School of Medicine.

    The researchers are also hopeful that the two proteins that are overexpressed or super abundant in locally advanced breast-cancer cells could serve as a biomarker for this type of cancer, making it easier to screen for. Early indications are that it is a reliable guide to the presence of this cancer 85 percent of the time, Schneider said.

 

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