The optimal follow-up and monitoring of patients with resected non-metastatic colon carcinoma were unclear until now. However, circulating tumor DNA (ctDNA) in the blood could solve this problem in practice, as a recent study has shown.
This small study included a total of 58 patients (34 men; 24 women) who all had non-metastatic stage I to III colon cancer and had already been resected. Eighteen of the participants received postoperative chemotherapy.
In the first month after resection of the tumor, blood was taken from the subjects for the determination of ctDNA. Afterward, a continuous blood sample was taken every three to six months. Patients were followed until metastases occurred for a median of 49 months.
The sensitivity and significance of the ctDNA measurement were compared with conventional monitoring methods such as computer tomography.
In patients who had a positive ctDNA result, recurrences were found in 77% of cases. Interestingly, the ctDNA in the blood check was able to detect the recurrence situation up to three months earlier than with conventional monitoring methods such as CT.
All 49 patients without measurable ctDNA for colon carcinoma remained recurrence-free over the follow-up period of 49 months (0%; 95%-KI: 0%-7.9%). In three patients, the researchers initially found increased ctDNA values in the blood, which, however, decreased continuously over the entire observation period.
Although these findings have yet to be verified in larger prospective studies, this current work already suggests that monitoring ctDNA levels in the blood of patients with colon carcinoma could support follow-up care in the future. Until now, CT images or the carcinoembryonic antigen (CEA) test were and are well suited to detect possible recurrences. In particular, the emerging temporal advantage of ctDNA response over CT would help to diagnose and treat recurrences even earlier in the future.
Resection of the tumor is still the treatment of choice in the presence of colon carcinoma. Although this operation is performed against a curative background, about 30-50% of patients suffer a relapse later on.
Since such recurrences, especially in the oligo-metastasized situation, are relatively easy to remove from the liver and lungs and there is still a potential chance of a cure, the early diagnosis of the recurrence in colon cancer is of great importance.
The present study provides the first evidence for the growing importance of personalized ctDNA analysis for the follow-up of patients with resected colon carcinoma at an early stage.
Source:
Wang Y et al, Prognostic Potential of Circulating Tumor DNA Measurement in Postoperative Surveillance of Nonmetastatic Colorectal Cancer. JAMA Oncol 2019; doi:10.1001/jamaoncol.2019.0512