Saliva provides early warning signs of cancer

Looking inside someone's mouth may one day involve more than dental care. It could enable early diagnosis of various cancers, leading to more effective treatment outcomes and better survival rates.

According to research presented at the 2008 American Association for Cancer Research (AACR) meeting in San Diego, analyzing the DNA in saliva can provide clues about the molecular damage that can lead to cancer. In particular, the investigators found that analyzing this DNA may help detect the early signs of head and neck squamous cell cancer (HNSCC).

While this research is still in its infancy, the researchers say sampling cells in saliva could become a cancer screening method for large populations, and dentists might play an important role in such testing.

"The test is a very noninvasive one and very patient-friendly," said Seema Sethi, M.D., of Henry Ford Hospital in Detroit, the lead researcher of the study. "At the same time, it was very good at differentiating those with cancer from healthy people without the disease."

At present, more than 40,000 Americans are affected by HNSCC, and approximately 12,000 die from it each year. The development of HNSCC in people at risk, such as smokers, takes many years, and most cases are diagnosed at an advanced stage when prognosis is poor. Often, the treatment is surgery that can lead to significant disfigurement.

"Patients are sometimes unable to eat and speak afterward," Dr. Sethi said. It would be much better if clinicians could diagnose this cancer before such drastic surgery is needed, she added.

In her study, Dr. Sethi and fellow researchers took saliva samples from 27 patients with HNSCC and 10 healthy participants and extracted DNA from the samples. They then examined 82 genes with known associations to HNSCC. Eleven genes were found to have some ability to predict the presence of HNSCC in the cancer patients. Upon further assessment, the researchers found that increases in a gene called PMAIP1 alone or together with a gene called PTPN1 identified all patients with HNSCC with 96% sensitivity and 90% specificity.

While emphasizing that this research is in its early stages, Dr. Sethi hopes that it could one day be used to screen for HNSCC on a widespread basis. The noninvasive test that Dr. Sethi and fellow researchers developed could be administered by dentists, she added. So just as dentists screen for oral cancer today, they may one day screen for more pervasive cancers such as HNSCC.

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