A new test involving a mouth rinse can identify those at risk for head and neck cancers, according to the Johns Hopkins Kimmel Cancer Center researcher who developed it.
“Commonly the way head and neck cancer is detected now is when somebody has symptoms – hoarseness or a lump on their neck,” said Dr. Joseph Califano. “Usually by that time it?s progressed to the point it?s more difficult to treat.”
His team examined 211 cancer patients and 527 individuals with no head or neck cancer to identify both the chemical markers that twist the cell?s genetic material into a cancerous formation as well as the genes affected.
Head and neck cancers account for approximately 3 to 5 percent of all cancers in the United States, according to the National Cancer Institute. These cancers are more common in men and in people over age 50. It is estimated that about 39,000 to 50,000 men and women in this country will develop head and neck cancer in any given year.
The test holds promise for screening those at high risk, including heavy smokers and alcohol drinkers, according to the study, published today in Clinical Cancer Research.
Researchers collected the rinsed saliva and filtered out cells thought to contain bits of chemically altered genes common only to head and neck cancers. Tumor and blood samples also were collected.
What they found was that small molecules called methyl groups clamp on to the DNA ladder structure of a gene. In the grip of too many methyl groups, these genes can incorrectly switch on or off in a process called hypermethylation which can lead to cancer, the researchers say.
The trick they faced was that methylation mistakes in other genes could be triggered simply by aging and amount to no more than fine lines and wrinkles, according to the paper.
“The challenge is to predict which hypermethylated genes are most specific to cancer,” Califano said. And because every cancer has a unique genetic fingerprint, combining several gene signatures for the disease rather than using single ones may identify a larger percentage of cancer patients.
Out of 21 hypermethylated genes, Califano?s team identified seven which were the best predictors of cancer within cell-laden saliva.
Screening for the same genes using a blood test was more accurate at detecting cancer in patients with the disease, however, it gave more false positives.
“Few tests can be perfect 100 percent of the time in identifying both normal and cancerous cells,” Califano said. “Because head and neck cancers are not widespread, it makes more sense to screen those at high risk and to focus on a test?s ability to accurately rule out healthy people.”
A saliva test, Califano said, is easy, painless and cheap, capturing cells from a wide area of the mouth. Some head and neck tumors do not shed genetic material into the blood, making the saliva test a better bet.
Commercial developers are already working on a marketable version, though Johns Hopkins investigators said more studies are needed to refine the test
