13 May Circulating Tumor DNA Linked to Recurrence After Colon Cancer Surgery
MedicalResearch.com Interview with:
Dr. Olsson
Louise Olsson MD PhD
Senior researcher
Department of Molecular Medicine and Surgery
Colorectal Surgery
Karolinski Institute
Stockholm, Sweden
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: I read a very interesting paper back in 2006 “Detection and quantification of mutation in the plasma of patients with colorectal cancer”. Only some 60 % of patients with early colorectal cancer were detectable in this way whereas patients with stage IV disease all had a high concentration of APC mutations in their plasma. So the prospects of using the method for example, screening of primary colorectal cancer seemed limited but I thought wow, this is the test to detect recurrences and generalized disease during follow-up after surgery for colorectal cancer. After some discussion we started to collect plasma samples from patients at the hospital where I worked and that´s how my research began.
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The main finding of the present study is basically the same as in 2006. All ten patients with distant metastases / recurrences had a positive ctDNA test. This came as no surprise and, logically, the findings in plasma were detectable prior to metastases were discernible on CT. But the overall lead time was fairly short, median three months for all patients in the study and to me the clinical significance of this time period is uncertain. However, many guidelines recommend longer intervals between CT scans than what was used in the study, so the potential gain may be better in real life.
MedicalResearch.com: What should readers take away from your report?
Response: All of the 45 patients with a negative ctDNA series had no recurrence and such a high negative predictive value is very promising. It seems you could trust a negative ctDNA outcome and use it as a triage test for radiology. If only patients with a positive ctDNA would need to be referred for CT scans during follow-up, it´s a win for the patient.
Another implication of the findings in this study was that even though ctDNA positivity preceded recurrence, lead time was far from long enough to affect any decisions on adjuvant chemotherapy.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: The findings need to be validated in a larger study, any clinical benefits for patients associated with lead time must be clarified and the role for ctDNA during surveillance of colorectal cancer established.
MedicalResearch.com: Is there anything else you would like to add?
Response: The overall risk of recurrence after radical surgery for all colorectal cancer stage II and III together according to nationwide data from Sweden is now one in six (16%). It seems ctDNA can further identify patients at very low risk of recurrence after surgery and this further challenges the current routine use of adjuvant chemotherapy in my view. It will be interesting to follow what will happen in the future.
I have no disclosures.
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Last Updated on May 13, 2019 by Marie Benz MD FAAD