With the current controversy related to the unreliability of the PSA test, the news of a new promising blood test to detect prostate cancer is very welcome.
PSA stands for prostate-specific antigens and levels of PSA in the blood are used as biomarkers for prostate cancer. Unfortunately, the method gives such a high rate of false positives that its usefulness has been questioned lately.
Researchers at the Dana Farber Institute tested the six-gene whole blood RNA transcript-based diagnostic test developed by Source MDx in Boulder, Colo in terms of accuracy, sensitivity, and specificity. Sensitivity is the ability of a test to detect the disease. Specificity is the ability of a test to rule out the presence of the disease.
The study revealed that the six-gene model [test] was more accurate than PSA alone at predicting cancer if you had it and no cancer if you didn’t. In addition, the test’s accuracy increased even more when sued in combination with the PSA test. Combined, the two tests exhibited a diagnostic accuracy of more than 90% in terms of sensitivity and specificity. In addition, the new test eliminated the majority of false positive results produced by the PSA test.
According to Dr. William K. Oh, clinical director of the Lank Center for Genitourinary Oncology at Dana-Farber
These findings are very encouraging and suggest that this new test could spare tens of thousands of men from undergoing an unnecessary biopsy. However, until we can verify our findings, it is important to recognize that the PSA test, despite its limitations, is still the best test available for diagnosing prostate cancer at this time.”
Currently, cancer experts are divided as to the benefits of prostate cancer screening using PSA. Men who tested positive for elevated levels of PSA are usually referred to have a prostate biopsy. Almost two thirds of men who tested positive in the PSA test would test negative for the biopsy. The prostate biopsy as such is painful, invasive, and can lead to complication. This high rate of “false positive” PSA test results underscores the need for a more accurate method for detecting prostate cancer, according to Dr. Oh.
The blood RNA transcript-based test presents a hope that someday prostate cancer screening would become a routine procedure using a highly reliable method similar to the Pap smear for cervical cancer and mammography for breast cancer.
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