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New Oral Cancer Tests: Crucial or Wasteful?

The New York Times
02 February 2009
By Laurie Tarkan

Though relatively rare, it is one of the easiest cancers to spot and diagnose. And if treated early, it is usually curable. So why do experts find oral cancer so vexing?

Despite the many advances against cancer in recent decades, the statistics on this form of it remain discouraging: more than 60 percent of cases are diagnosed in the late stages, and the five–year survival rate is a disappointing 59 percent. Moreover, oral cancer is increasing in people traditionally at low risk, a phenomenon partly attributed to the rise of the cancer–causing human papillomavirus, or HPV, which can be transmitted through oral sex.

Now some dentists – whose visual examinations have long been a first line of defense against oral cancer – are using screening devices that they say may help identify cancers and premalignant lesions.

But these new tests have set off a debate over cost and effectiveness. Experts are divided on whether they will reduce mortality from oral cancer or simply lead to a wave of expensive and unnecessary biopsies.

An estimated 35,300 Americans learned they had oral cancer last year, and about 7,600 died from the disease. For survivors, oral cancer can be painful and disfiguring, and can destroy the ability to taste and enjoy food. Smokers and heavy drinkers are considered at highest risk for the disease, but 25 percent of those who receive a diagnosis are neither. Still, the lifetime risk of oral cancer – about 1 in 99 – is very low compared with breast and prostate cancer.

Because the disease is often diagnosed late, many experts believe that screening can reduce mortality. This has not been proved, partly because there is a dearth of research on oral cancer.

Indeed, no one knows for sure whether even a visual examination in the dentist’s office saves lives, though most oral cancer experts believe it does. That hypothesis is based on the proven benefits of early detection of other cancers and the better survival rates in cases that are detected early – about 80 percent five years after diagnosis.

“We know in every cancer where we’ve seen a reduction in the death rate – cervical, skin, breast – that what has brought the death rate down is early detection,” said Brian Hill, an oral cancer survivor from Laguna Niguel, Calif., and a founder of the Oral Cancer Foundation, a nonprofit group.

One large study from India, where oral cancer rates are much higher than in the United States, found that when high–risk subjects had a visual exam, it reduced the mortality rate by 34 percent compared with control subjects who were not screened. But some experts say this research cannot be applied to the general population or to Americans.

The American Cancer Society and the American Dental Association recommend a regular visual exam. But even though it is generally covered by insurance, not all dentists perform it.

“Studies show that most dentists don’t leave dental school feeling comfortable doing it,” said Dr. Michael A. Siegel, a professor and the chairman of diagnostic sciences at Nova Southeastern University College of Dental Medicine in Fort Lauderdale, Fla.

Now medical companies are marketing several new screening tests and devices to dentists, saying they will vastly improve early detection of oral cancer. The devices, which can cost several thousand dollars, use rinses, dyes and different types of lights to detect abnormal cells.

Some experts say the new technology will lead to earlier detection, if only by encouraging dentists to do a screening exam. “The tests change the paradigm by which they practice,” Dr. Siegel said. “Simply because it’s new, they say, ‘I’m going to use it.’ ”

They can also charge for the test, and some insurers have started covering it.

“We’re advocates of using these devices because there are some things your eye might miss,” Mr. Hill said.

Yet no extensive studies of the general population show that these devices are any better than the naked eye for screening, and they have not been shown to reduce mortality.

“There’s no evidence for their use by front–line screeners, no evidence,” said Dr. A. Ross Kerr, an assistant professor at the New York University College of Dentistry.

In small studies, the devices successfully detected potentially malignant lesions that experienced specialists missed with the naked eye. For example, in one group of subjects a scanning system called the VELscope identified all of the cases of moderate to severe dysplasia, or potentially precancerous cells, compared with just 68 percent for a visual exam, said the study’s author, Dr. Edmond Truelove, a professor and the chairman of oral medicine at the University of Washington. (Dr. Truelove does not receive financing from LED Dental, the company in British Columbia that makes the VELscope.)

Another study of 688 high–risk patients examined by experienced specialists found that when only a visual exam was performed, the specialist requested a biopsy of 12 of the 30 lesions that turned out to be cancerous. Of those who also used toluidine blue, a dye that is a component of a test called ViziLite Plus, 29 of the 30 lesions would have been biopsied, said the study’s author, Dr. Joel Epstein, a professor of oral medicine at the University of Illinois, Chicago.

But he added, “What we don’t know is what happens if we use the same technique in a low–risk population by people with less experience.” (Dr. Epstein said that in the past he had received compensation from Zila Pharmaceuticals, which makes ViziLite, and is currently receiving financing from the company for a small study.)

The screening tests can cost the patient $35 to $65, though some dentists do not charge extra for it. And the tests have a high false–positive rate that may lead to unnecessary biopsies. If a suspicious lesion is detected, dentists typically ask the patient to return in two weeks to see if it has improved. If not, the patient may be given a biopsy or referred to a specialist.

Some dentists are telling their patients that because of the rise of oral cancers linked to HPV, every adult, not just the traditionally high–risk groups, should be screened with these devices.

Yet oral cancers associated with the papillomavirus are still rare, and they typically occur near the base of the tonsils and the back of the tongue, where they are very difficult to see at the earliest stages, even with the use of these devices, said Dr. Maura L. Gillison, a professor of medicine at Ohio State who is a leading expert on oral HPV.

Dr. Mark Lingen, an associate professor of pathology at the University of Chicago Medical Center, agreed. “If you can’t get back there to see it,” he asked, “how is that device going to help you?”

But Dr. Epstein says the devices may help. “If you’re someone with a high risk of HPV exposure, meaning that you’ve had oral sex with multiple partners, you need to be examined carefully,” he said. “Higher–risk people could maybe benefit from some of these adjuncts.”

Dr. Truelove, who did the VELscope study, said he would not recommend expensive screening for normal individuals, but he added, “On the other hand, a low–cost test, say $5, that enhances a clinician’s ability to detect something they might otherwise miss is potentially useful, particularly in people who have some increased risk of the disorder.”

Researchers are working on the holy grail of oral cancer screening: a test that can analyze saliva for early gene changes that could lead to the disease.

Most experts agree that everyone should have an annual visual exam and that it should be thorough. A dentist or trained hygienist should examine the cheeks, the gums, the floor of the mouth, the area behind the teeth, the palate and the tonsil area, pulling the tongue forward – often to the point of gagging. The dentist should also feel the lymph nodes of the neck, sometimes the first visible sign of oral cancer.

“The emphasis should also be placed on educating physicians about oral cancer,” said Dr. Kerr, of N.Y.U. Only 60 percent of adults see a dentist at least once a year, he continued, adding, “The 40 percent who never go to the dentist are likely to have the highest risk factors.

“When I teach my students,” he said, “I say at the end of the day, all you need is to have one patient with an early cancer that you picked up and you will do this for the rest of your career.”

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