Friday, January 27, 2012

Non-invasive brain cancer diagnosis made possible

Even though cancer is always bad, the brain is a particular bad place to develop it. It is a densely packed space filled with brain cells and the wires that connect them, which pretty much control our whole body. Brain tumours are sometimes hard to detect, and to confirm a diagnosis invasive surgery is needed, such as a biopsy. For hard to reach tumours, however, a biopsy or surgery is impossible. Scientists from the University of Texas have eliminated the need for such procedures to confirm a diagnosis, by making an alternative, non-invasive test. The test is suitable for some of the deadliest, yet not all forms of brain cancer. It is nevertheless a great improvement for the tricky diagnostics that are involved with such tumours, which is in turn beneficial for treatment.

Patients with gliomas, a tumour derived from other cells than nerves carrying out typical brain tasks, benefit from the newfound non-invasive test. 80 percent of the patients with a glioma that is not highly aggressive carry a genetic mutation which can be detected in the form of its product: a modified protein. With MRS, as the new test is known in its abbreviated form, protein levels associated with the mutated gene are measured, which tells the doctors something about the growth of the tumour. In this case, the protein is described as a disease marker, or more commonly, a biomarker.

Current scans
MRS is not the only non-invasive diagnostic tool for brain cancers. Related scanning techniques such as MRI and CT are often performed to get an idea of what the tumour looks like. The problem is, however, that a definite diagnosis cannot be made before a pathologist gets his hands on a slice of tissue to determine what it is that the patient is dealing with. Because the protein measurements are specific for a particular form of glioma, the researchers eliminate the step for a confirmation by invasive surgery.

Brain cancer is often associated with poor prognosis, and gliomas are often incurable. Glioblastoma is one of the most aggressive forms, and is sadly also the most common. Treatment often consists of chemotherapy or radiation therapy, despite new therapies with things such as nanoparticles being underway. Because the treatment is not quite cancer-specific, it damages surrounding tissue, which can wreak havoc in the brain. Measurements of protein levels as an indication of how the patient is doing is therefore helpful to assess what the best options are. The downside of the new diagnostic tool is that it does not work for aggressive gliomas: these forms do not rely on the aforementioned genetic mutation.
Dark spot surrounded by white border: a glioblastoma.
With the form of MRS being used, a protein is used as a biomarker: it is an indirect measurement of how bad the disease is. We have found many biomarkers in the last decades, which help us in diagnosis of many diseases. Prostate cancer is perhaps one of the most well-known examples, as doctors commonly measure the levels of a protein called PSA. It is produced by the prostate. That means higher levels indicate a bigger tumour. Other biomarkers may work in different ways, but the idea remains the same. Because they are often easier to measure than actually assessing the problem itself, a lot of research is devoted to discovering new biomarkers. It can also tell us something is wrong quite early on: protein levels can change before a tumour is detectable. This time it is brain cancer that has seen some success, but it is likely that there are many more new diagnostic tools based on protein levels yet to come.

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