Sore throat, swollen glands, and pain or difficulty swallowing. Almost everyone suffers from it at some point. Usually it is a simple cold, but these are also typical symptoms of mouth and throat cancer. It is therefore not surprising that many patients are only diagnosed at a late stage. Every year doctors diagnose throat cancer in 400 Dutch people after an examination in the mouth or throat. At that point, in many cases, the cancer has progressed to such an extent that treatments are not effective. Nearly half of patients do not live longer than five years after diagnosis.
Behavior as a predictor
American researchers have developed a test that should detect mouth and throat cancer at an early stage, so that doctors can start treatment in time. In the test, they take some saliva from the patient’s mouth and study the microorganisms in it. The composition of the micro-organisms in the saliva and their behavior differ between healthy people and patients with mouth or throat cancer. The molecular processes of those microbes are slightly different then. This became apparent when scientists compared the saliva of 71 mouth and throat cancer patients with that of 171 healthy subjects.
To visualize the behavior of micro-organisms, you can think of them as a large choir, with each choir member having a book full of songs. In a body where a tumor is growing, some singers will sing sad songs from the book, others will sing classical music. In a healthy body, most singers sing pop and rock songs. Based on the songs you hear, you know in which environment the choir is located: a healthy environment, or an environment with tumors.
True microorganisms do not display their behavior with song. Yet scientists discover this behavior by investigating which properties (genes) are active. When a gene is turned on, the microorganism translates that piece of DNA into the genetic molecule RNA. That is the messenger that tells the cell which processes to take place (which songs to sing). The scientists extract this RNA from the microorganisms in the patient’s spit and read it with a special device. In this way, with the help of computers, they get a good idea of which micro-organisms are present and how they behave.
On the road to approval
In each test, the computer compares the micro-organisms and their behavior with those of patients and healthy individuals. If they are most similar to those of mouth and throat cancer patients, the test is positive. Unfortunately, the cancer test is not one hundred percent accurate. The first study – which has yet to be reviewed by fellow scientists – indicates that the test shows the presence of a tumor in more than eight out of ten patients, and misses it in the other two.
“Nevertheless, that’s a good score,” says Marcel de Zoete, microbiologist and associate professor at UMC Utrecht. He is not involved in the research himself, but is also working on the relationship between microbes and diseases. “It means that eighty percent of patients can be diagnosed and treated earlier.”
The test is also sometimes incorrect the other way around: it then detects cancer in a healthy person, a ‘false positive result’. In 91 subjects, representative of the (American) population, the test was incorrect only twice. But in high-risk groups such as over-50s, (ex-)smokers or patients with cardiovascular disease, the test detected a tumor ten times more often, while there was none. Therefore, after a positive result, doctors will have to perform additional physical examinations such as an endoscopy, biopsy or MRI.
For the time being, the cancer test is not yet on the market, but in May he did receive the so-called Breakthrough status from the FDA, the US Food and Drug Administration. In doing so, the agency recognizes, among other things, that the cancer test is a promising method with clear advantages, that it is an improvement on existing diagnoses and that there is not yet a good alternative for the test. This status does not mean that the method has been approved for use, but the US agency will assess the method more quickly as a result.
It is still unclear whether a tumor alters the behavior of micro-organisms or whether the behavior of micro-organisms makes tumor growth possible. In the latter case, scientists could use the behavior of micro-organisms to predict whether a person has an increased risk of mouth and throat cancer.
“But the research is not yet that far,” warns De Zoete. “We first have to follow people and the microorganisms in their mouths for a long time to find out which of the two is the cause.” If it turns out that certain microorganisms and their behavior are the culprit, scientists can take action. “For example, by inhibiting certain behavior of bacteria with substances or by catching specific bacterial species with probiotics or highly selective antibiotics,” says De Zoete.
Source: Kennislink by www.nemokennislink.nl.
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