Originally published January 19 2009
Breast Cancer Saliva Test to Make Dangerous Mammograms Obsolete
by David Gutierrez, staff writer
(NaturalNews) Researchers are working to develop a saliva test for breast cancer that could vastly reduce the use of dangerous and invasive breast cancer screening techniques such as mammograms.
"This will be a noninvasive, quick means of detection," said lead researcher Charles Streckfus, a professor of diagnostic sciences at the Dental Branch of the University of Texas (UT) at Houston. "With it, dentists will be able to catch cancers before a woman can feel a lump."
Researchers have discovered that the onset of breast cancer changes the density of different proteins excreted by the salivary glands. In the current study, published in the journal Cancer Investigation, Streckfus and other researchers from the UT-Houston Dental Branch and Medical School compared the protein levels found in the saliva of 10 women with breast cancer, 10 healthy women and 10 women with a type of tumor called fibroadenoma.
Fibroadenoma is the most common kind of benign breast tumor.
"Saliva is a complex mixture of proteins," said researcher William Dubinsky. "We go through a process that compares different samples by chemically labeling them in such a way that we can not only identify the protein, but determine how much of it is in each sample. This allows us to compare the levels of 150-200 different proteins in cancerous versus non-cancerous specimens to identify possible markers for disease."
The researchers identified 49 proteins that were present at different levels between the three groups. These proteins should hypothetically allow doctors to use such a saliva test to alert them when a woman has a tumor, and to determine whether it is cancerous or benign.
"This is a unique finding," Streckfus said, "as it targets both the benign and malignant tumor, which could potentially reduce the number of false positives and false negatives associated with current cancer diagnostics".
Previously, the same team of researchers was able to correctly detect whether a woman had breast cancer 85 percent of the time, using only one saliva protein as a marker. With 49 different markers, Streckfus says that the accuracy of the test should be closer to 95 percent.
In the current method, the saliva sample is placed onto a hand-held, gold-plated chip or lab dish, developed by UT-Austin biochemists. A laser analyzes the protein content of the sample.
"I see this as a future public health service by dentists," Streckfus said. "Most folks, especially women and children, visit the dental office way more often than they ever see the physician. Saliva is a non-invasive, quicker way for detection."
Many obstacles remain before this test could be available, however. The first step is more studies to confirm the effectiveness of the protein markers as diagnostic tools in a larger group of patients. Streckfus and colleagues hope to launch a large, multicenter clinical trial of the test within the next two years, and to apply for FDA approval within five.
The only saliva test currently approved by the FDA is one for HIV/AIDS.
A saliva test for breast cancer has many advantages over current diagnostic methods such as ultrasounds, mammograms, biopsies and blood tests. It would be far less invasive and expensive than most such tests, and have a much higher accuracy rate than blood tests, which are not currently favored for breast cancer diagnosis due to their poor accuracy.
The higher accuracy of a saliva test comes in part from the fact that saliva proteins are much easier to detect than the proteins in blood, Dubinsky said.
"In the case of breast cancer, saliva analysis has been used to monitor patient response to chemotherapy or surgical treatment of the disease," said Professor Damien Walmsley, scientific adviser for the British Dental Association. "The mouth itself is a good indicator of an individual's overall health, and dentists already play an important role in diagnosing and detecting oral cancers."
Streckfus said that a saliva test would be particularly valuable in places where mammography centers are rare, such as in many Third World countries, or in breast cancer survivors who need to be regularly monitored for potential cancer recurrence.
Regular use of mammograms is not only expensive and emotionally distressing, but can also be dangerous. Because women are exposed to X-ray radiation as part of the mammogram procedure, regular mammogram use actually increases women's risk of developing various cancers. For this reason, mammograms are not normally performed for women under the age of 40, in whom the risk of breast cancer is relatively low unless symptoms are present.
But Streckfus warned that a saliva test cannot utterly replace mammograms, because the saliva test is unable to determine which breast contains the tumor.
Nonetheless, cancer patient advocates have greeted the new research as promising. According to Leonard Lichtenfeld, deputy chief medical officer for the American Cancer Society, the saliva test will one day be "a terrific advance."
"I think advances like this test portend the day when we'll be able to diagnose disease that would be invisible using today's technologies," Lichtenfeld said. "[Patients will] be able to be diagnosed and treated before they would otherwise know they have the disease."
Streckfus and colleagues are also researching whether saliva tests can be used to diagnose other cancers, including of the cervix, uterus, head, neck and ovaries. Another group of researchers, at Johns Hopkins Kimmel Cancer Center, is also working on a saliva test for head-and-neck cancer. According to Lichtenfeld, the Johns Hopkins team is farther along than the UT-Houston team, because their test relies on genetic rather than protein markers.
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