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The purpose of this study is to develop a diagnostic blood test for breast cancer. The concept is based on the premise that breast cancers shed sufficient quantities of DNA into plasma to be detected using methylation-specific PCR. Initial testing of the method was disappointing because relatively few cancers were detected in serum or plasma from documented breast cancer patients. We modified our methodology to greatly increase the sensitivity of the assay. Concurrently, we tested a larger panel of genes for methylation in breast cancers of various histologic types. The improvement of sensitivity resulted in some loss of specificity, with positive methylation signals detected in white blood cells and normal breast from some individuals. This problem appeared to be somewhat biased toward particular genes, such as BrCAl. Using the modified MSP detection method and a panel of 4 sensitive and relatively specific gene markers, we were then able to detect positive signals in plasma for 21 of 31 cases (62%) with methylation of at least one of the genes in the tumor tissue. Overall, this project has demonstrated potential for using methylation specific PCR to detect breast cancer derived DNA in patients' blood. However, the project has also identified potential issues with regard to sensitivity and specificity that would need to be addressed before application as a clinical assay. |
