Guest guest Posted March 31, 2009 Report Share Posted March 31, 2009 PCR testing can detect very small amounts of genetic material in a biospecimen sample, such as a gene translocation t(14:18) which produces pro-survival protein, BCL-2, in many lymphomas. When the PCR test is negative (a good result), it means that there may be no abnormal cells in the blood or marrow, which might be described as a molecular remission. Analogy: A standard bone marrow test is like taking a sample of a pool with a scoop net in the dark. The test is only conclusive if leaves are found, because the sample may have missed leaves floating elsewhere in the larger pool. PCR testing is like examining the same sample for tiny fragments of substances that exist only in leaves. Thus, a negative finding with PCR testing provides greater confidence that the bone marrow is clear of the abnormal cells. The clinical significance of a molecular remission is still not clear, but achieving this kind or response has been associated with longer duration of response among the participants in some studies. PCR tests are generally given after a complete response to treatment has been determined using CT and a bone marrow biopsy, mainly in clinical trials. The analytical sensitivity of PCR is 1 tumor cell in 100,000 normal cells. A limitation of the test is that it can only show the status of the compartment tested: the blood or marrow. A conversion to negative appears to be a good prognostic indicator, but not definitively, because the test can't determine the t:14:18 status in lymph nodes and other areas. See http://www.lymphomation.org/tests-scans.htm#bcl-2 Karl www.lymphomation.org Quote Link to comment Share on other sites More sharing options...
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