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DNA-based blood test predicts risk for recurrent colon cancer
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Among patients who underwent resection of stage 2 colon cancer, a blood test that detects circulating tumor DNA accurately identified those with a high risk for cancer recurrence, according to the results of a prospective study conducted by Johns Hopkins and University of Melbourne researchers.
If confirmed in future studies, this test could help clinicians identify patients who may benefit from adjuvant treatment at the time of diagnosis, according to a press release.
“Most patients with stage 2 colon cancers will be cured of the disease after surgery alone. However, some of these cancers will recur, and we need to improve our diagnostic approaches to detect recurrence earlier than it can be found with current, conventional methods,” Bert Vogelstein, MD, co-director of the Ludwig Center at the Johns Hopkins Kimmel Cancer Center, said in the press release.
Bert Vogelstein
Vogelstein and colleagues used massively parallel sequencing-based assays to determine if postoperative circulating tumor DNA (ctDNA) analysis could detect minimal residual disease in 1,046 plasma samples collected from 230 patients with resected stage 2 colon cancer from 13 Australian hospitals (median age, 65 years; 57% men). Samples were collected between 4 and 10 weeks after surgery and every 3 months after for up to 2 years, and patients also underwent a CT scan every 6 months after surgery for 2 years.
Initially, they also genetically sequenced the resected primary tumor tissue and found at least one somatic mutation in 99.6% of the specimens.
The researchers detected ctDNA in 20 patients, 80% of whom experienced cancer recurrence within about 2 years. Moreover, only 10% of the 164 patients whose blood tested negative for ctDNA experienced cancer recurrence.
Of those who tested positive, six received adjuvant chemotherapy and 14 did not. Among the six patients who received adjuvant chemotherapy, three experienced cancer recurrence detected by CT scan, and among the 14 patients who did not receive adjuvant chemotherapy, 11 experienced cancer recurrence. Fourteen patients in whom ctDNA was not detected also experienced cancer recurrence.
Nickolas Papadopoulos
Kenneth Kinzler
“Although this and other DNA-based blood tests are not perfect, this study shows that when we find tumor DNA circulating in the blood of cancer patients, recurrence is very likely,” Nickolas Papadopoulos, PhD, professor of oncology at the Johns Hopkins University School of Medicine and member of its Kimmel Cancer Center, said in the press release.
Currently there are no FDA-approved DNA-based blood tests for cancer, but several are in development, according to the press release. However, their cost estimates are high and reimbursement is uncertain.
“There is mounting evidence that ctDNA is a viable approach for earlier detection of cancer recurrence, and more research is underway to refine the technology, improve its sensitivity and determine the best testing intervals,” Kenneth Kinzler, PhD, co-director of the Ludwig Center at the Johns Hopkins Kimmel Cancer Center, said in the press release. – by Adam Leitenberger
Disclosures: Kinzler, Papadopoulos, Vogelstein and another researcher report they are founders of PapGene and Personal Genome Diagnostics and members of the scientific advisory boards of Morphotex and Sysmex Inostics. Please see the full study for a list of all other researchers’ relevant financial disclosures.
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