Researchers have, in a study published in Science Translational Medicine, revealed details of a new test that can be used to predict recurrence of colon cancer.
The test was developed by scientists at the Johns Hopkins Kimmel Cancer Center and University of Melbourne. The test spots bits of cancer-related DNA circulating in the blood to accurately predict the likelihood of the disease’s return in some — but not all — of a small group of patients with early-stage colon cancer. Researchers are optimistic that the test could eventually help clinicians decide which patients need additional treatment at the time of their initial cancer diagnosis of stage 2 cancer.
Stage 2 tumors, in general, have invaded nearby tissues but not spread to other organs, and uncertainty has long surrounded the question of whether chemotherapy prescribed after surgical treatment is beneficial.
For their study researchers followed 230 stage 2 colon cancer patients in 13 hospitals in Australia for four years, beginning in 2011, collecting more than 1,000 blood samples from them. After scanning the genetic sequences of tissue taken from the patients’ tumors during surgery, the scientists, identified at least one colon cancer-related gene mutation in the patients’ original tumor.
Over time, they tracked each patient’s cancer-related mutation in his or her blood samples, taken between four and 10 weeks after their surgery and every three months afterward for up to two years. The tracking used highly sensitive genetic tests to locate and amplify DNA found there. Patients also underwent a CT scan of their entire body every six months after surgery for two years.
Among the 230 patients, 20 had cancer-linked DNA fragments in their blood, including 14 who did not to receive additional chemotherapy and six who did. Of the 14, 11 developed a recurrence, found on a CT scan, during the study. Of the six who received additional chemotherapy, three experienced a recurrence of their cancers during the study period. An additional 14 patients experienced cancer recurrences, but their blood tests showed no cancer-linked DNA.
Currently, some 40 percent of patients with stage 2 colon cancers are considered at risk for recurrence as a result of measuring how far the cancer has grown into the intestine’s wall, the number of lymph nodes examined during surgery, and whether the cancer has spread to blood or lymphatic vessels. Those deemed at higher risk are usually treated with chemotherapy following their surgery, but efforts to demonstrate the benefit of such additional therapies have been hampered by the lack of large-scale studies with the statistical power to show any benefit in terms of survival, say the researchers.
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