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Epigenetics offers new options for cancer diagnosis.

Epigenetics is the study of molecular modifications that switch a person's genes on and off, telling cells how they should behave. Recent research indicates that if those epigenetic markings are disrupted, causing a gene to become incorrectly active or silent, a healthy cell could become diseased.

Researchers are beginning to uncover the mechanism behind these switches and the circumstances under which changes occur. This research is bringing new insight into human biology, particularly the understanding of diseases such as cancer, diabetes, and schizophrenia.

Every human has hundreds of genes, which, when working properly, keep the body healthy. The genes can be disrupted by damage directly to their DNA; however, scientists now realize that epigenetic changes also may be responsible. Genetics can explain only a small proportion of a person's predisposition to complex diseases. Epigenetics could provide the missing link. What is exciting researchers is that, unlike genetic changes, epigenetic changes appear to be reversible, which may open the possibility of a whole new area of treatments.

One type of epigenetic change in cancers is DNA methylation. Two drugs, decitabine and azacitidine, are being used to remove the aberrant mythylation, reactivating genes that had been silenced. The success of these drugs in treating myelodysplastic syndrome, a bone marrow disorder that disrupts the formation of blood cells, has led to hopes for other types of cancers. The understanding of epigenetic changes not only may reveal how tumors develop and become malignant but also has potential in the early detection of cancer.

Epigenetic markers could be used for diagnosis. Tumors release tiny bits of epigenetically altered DNA into the bloodstream. A blood test for abnormally methylated DNA could help catch cancer in its early stages. Researchers have developed a method to detect as little as three picograms of methylated DNA; it will spot as few as three cancer cells in a tissue sample.

The tests that are being developed may determine not only whether a patient has a certain cancer but also the severity of the cancer and the likelihood that it will respond to a particular treatment. It is hoped that the first product, a screening test for colon cancer, will be on the market in 2008. The test is several times more likely to spot a tumor than the current test, which measures the amount of blood in a stool sample. Because the process is so sensitive, only a standard blood sample is required.

Work is being done on diagnostics for three more cancers: non-Hodgkin lymphoma, breast cancer, and prostate cancer. The ultimate goal is a human epigenome-mapping project that would identify the full range of epigenetic variations possible in the human genome. Such a map could reveal the missing links among genetics, disease, and the environment.

Researchers predict that the methylation status of 100% of human genes will be mapped by the end of 2008. In the future, epigenetic screening for common cancers may be a part of regular medical check-ups.

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Yang, N., Coukos, G., & Zhang, L. (2008). Micro-RNA epigenetic alternations in human cancer: One step forward in diagnosis and treatment. International Journal of Cancer, 122(5), 963-968.

Deborah McBride, RN, MSN, CPON[R], Contributing Editor

Contributing Editor Deborah McBride, RN, MSN, CPON[R], is a nurse at the Kaiser Permanente Oakland Medical Center and a faculty member at Samuel Merritt College in Oakland, CA.
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Title Annotation:NEW TREATMENTS, NEW HOPE
Author:McBride, Deborah
Publication:ONS Connect
Geographic Code:1USA
Date:Apr 1, 2008
Words:557
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