Lead investigator Joseph Califano, M.D., says his group at Johns Hopkins asked 211 head and neck cancer patients and 527 individuals without cancers of the mouth, larynx or pharynx to brush the inside of their mouths, then rinse and gargle with a salt solution.
The researchers collected the rinsed saliva and filtered out cells thought to contain one or more of 21 bits of chemically altered genes common only to head and neck cancers. Tumor and blood samples also were collected.
The cellular mishaps occur when 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. “Mass-methylation” of particular genes can lead to cancer, the researchers say. Methylation mistakes in other genes could be triggered simply by aging and amount to no more than fine lines and wrinkles.
“The challenge is to predict which hypermethylated genes are most specific to cancer,” says Califano, an associate professor of otolaryngology – head and neck cancer and oncology at Johns Hopkins. And because every cancer process involves a unique genetic fingerprint, combining several gene signatures for the disease rather than using single ones may identify a larger percentage of cancer patients.
Califano and his colleagues’ report in the January 1 issue of Clinical Cancer Research noted that of 21 hypermethylated genes, seven of them were the best predictors of cancer within cell-laden saliva. Of the seven best, he tested panels of three to five genes on saliva rinses.
One panel correctly identified 66 out of 154 patients (42.9 percent) with the disease, and accurately ruled out the disease in 203 of 248 healthy subjects (81.9 percent).
Califano’s team used a different set of seven hypermethylated genes among blood samples as well. Although the blood test was more accurate than the saliva test at detecting cancer in patients with the disease (34 out of 37), there was a trade-off in the number of healthy individuals it spotted (53 of 173).
“Few tests can be perfect 100 percent of the time in identifying both normal and cancerous cells,” says Califano. “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.”
Califano notes that tests designed for broader populations, like PSA, focus on identifying a widespread disease in large numbers of people.
A saliva test, Califano says, is easy to do, 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.
The Johns Hopkins investigators said more studies are needed to refine the test by uncovering additional hypermethylated genes that play a role, and to automate the test before multi-institutional clinical trials can begin. One of the first clinical uses for such a test could be to detect recurrence in current head and neck cancer patients.
There are nearly 50,000 cases of head and neck cancer diagnosed in the U.S. annually. Most are found when the disease has spread, and less than a year after diagnosis, many recur. Causes include heavy tobacco and alcohol use. Other head and neck cancers are caused by the sexually transmitted human papillomavirus.
Vanessa Wasta | EurekAlert!
How prenatal maternal infections may affect genetic factors in Autism spectrum disorder
22.03.2017 | University of California - San Diego
22.03.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
22.03.2017 | Materials Sciences
22.03.2017 | Physics and Astronomy
22.03.2017 | Materials Sciences