Results of a 2015 study at London’s Institute of Cancer Research show that a simple blood test gives highly accurate predictions of breast cancer recurrence. On average, the test was able to detect recurrences nearly eight months prior to the development of noticeable signs of disease.
CBS news reports that the study followed 55 women who had successfully completed treatment for early-stage breast cancer with chemotherapy and surgery. These women were also considered at high risk for relapse. Using a process called mutation tracking, the researchers identified DNA mutations in cancer cell samples from each woman, then developed a blood test that can detect circulating DNA in the patient’s blood. Researchers tested each patient’s blood soon after surgery, then every six months.
Fifteen of the 55 study participants eventually had recurrences of their cancers, and the blood test accurately predicted 12 of those relapses. The blood test predicted the relapses an average of 7.9 months earlier than other methods of detection. Cancer had recurred in the brains of the three patients whose relapses were not detected by the test; the BBC suggests that the blood-brain barrier may have prevented detection of the tumor DNA in the blood of these women. In addition, the test detected cancer DNA in the blood of one patient who did not actually relapse. The study found that women with detectable cancer DNA in their bloodstreams were 12 times more like to experience a recurrence of their cancer.
Genetic Engineering & Biotechnology News notes several potential benefits of this “liquid biopsy.” It is a far less invasive procedure than a traditional biopsy in which doctors remove suspicious cells from the body for testing. It is quick and easy to complete on a routine basis, and it can detect tumors long before they are visible through traditional methods such as imaging scans.
The test is also able to detect genetic mutations in cancers. The results of this test offer the potential to treat a cancer recurrence before it has extensively metastasized and before it has undergone extensive mutations that can make it more resistant to treatment. The study suggests that the test may detect abnormalities in cells before they have actually become cancer, perhaps creating the opportunity to prevent an impending relapse before it occurs. This test can also reveal residual cancer cells that may be present immediately after surgery or chemotherapy and are not visible using current imaging techniques. In addition, tracking the gene mutations of many individual cancers provides insight into the exact ways in which these cells evolve to decrease their susceptibility to drug treatments.
Because the test collects customized DNA profiles of each individual patient’s cancer cells, it may also be possible for doctors to use this information to create more personalized treatment plans with the most effective drugs to target the cancer.
The next steps for this research are to undertake trials on a larger scale and to investigate whether this type of testing would also be effective for other types of cancer. Routine use of this test is likely still several years away. Although the blood test itself is fairly inexpensive, the initial analysis of the cancer DNA for each patient is a costly process.
Although this study has not yet resulted in changes to standard detection and treatment practices, it represents an important step forward in the development of new early detection methods. It may also lead to more personalized and effective drug treatments for breast cancer and other types of cancer.
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