Postoperative circulating tumor DNA as markers of recurrence risk in stages II to III colorectal cancer

Abstract

Background: Precise methods for postoperative risk stratification to guide the administration of adjuvant chemotherapy (ACT) in localized colorectal cancer (CRC) are still lacking. Here, we conducted a prospective, observational, and multicenter study to investigate the utility of circulating tumor DNA (ctDNA) in predicting the recurrence risk.

Methods: From September 2017 to March 2020, 276 patients with stage II/III CRC were prospectively recruited in this study and 240 evaluable patients were retained for analysis, of which 1290 serial plasma samples were collected. Somatic variants in both the primary tumor and plasma were detected via a targeted sequencing panel of 425 cancer-related genes. Patients were treated and followed up per standard of care.

Results: Preoperatively, ctDNA was detectable in 154 of 240 patients (64.2%). At day 3-7 postoperation, ctDNA positivity was associated with remarkably high recurrence risk (hazard ratio [HR], 10.98; 95%CI, 5.31-22.72; P < 0.001). ctDNA clearance and recurrence-free status was achieved in 5 out of 17 ctDNA-positive patients who were subjected to ACT. Likewise, at the first sampling point after ACT, ctDNA-positive patients were 12 times more likely to experience recurrence (HR, 12.76; 95%CI, 5.39-30.19; P < 0.001). During surveillance after definitive therapy, ctDNA positivity was also associated with extremely high recurrence risk (HR, 32.02; 95%CI, 10.79-95.08; P < 0.001). In all multivariate analyses, ctDNA positivity remained the most significant and independent predictor of recurrence-free survival after adjusting for known clinicopathological risk factors. Serial ctDNA analyses identified recurrence with an overall accuracy of 92.0% and could detect disease recurrence ahead of radiological imaging with a mean lead time of 5.01 months.

Conclusions: Postoperative serial ctDNA detection predicted high relapse risk and identified disease recurrence ahead of radiological imaging in patients with stage II/III CRC. ctDNA may be used to guide the decision-making in postsurgical management.

Keywords: Adjuvant chemotherapy; Circulating tumor DNA; Minimal residual disease; Recurrence risk; Stage II/III colorectal cancer.

Conflict of interest statement

Y. Shao and H. Bao report to be employees of Nanjing Geneseeq Technology, Inc. China. The remaining authors declare that they have no conflict of interest.

Figures

Fig. 1

Flowchart depicting the patient enrollment, sample collections and evaluable population. ACT, adjuvant chemotherapy; CEA, carcinoembryonic antigen; CRC, colorectal cancer; CT, computed tomography; ctDNA, circulating tumor DNA; pre-op, pre-operation; post-op, postoperation

Fig. 2

Association of postoperative and post-adjuvant chemotherapy ctDNA status with recurrence risk. a Kaplan–Meier estimates of recurrence-free survival (RFS) according to ctDNA status at day 3–7 postoperatively. b The nomogram constructed by selected clinicopathological factors, recurrent-mutated genes, and ctDNA status at day 3–7 postoperatively for predicting 1-year and 2-year RFS. Mut, mutant; Wt, wild-type. c The clinical courses together with ctDNA statuses of 17 out of 20 ctDNA-positive (at day 3–7 postoperation) patients who received adjuvant chemotherapy (ACT). d Kaplan–Meier curves of RFS of the 137 patients who had plasma samples drawn after ACT, stratified by ctDNA status at first sampling point post-ACT

Fig. 3

Association of ctDNA analyses with early detection of recurrence. a Kaplan–Meier curves of recurrence-free survival of the 125 patients who were included in the serial post-definitive treatment analysis, stratified by serial ctDNA status. b ctDNA profiling results and the corresponding clinical courses of the 23 relapsed patients included in the serial post-definitive treatment analysis. c Comparison of time from surgery to disease recurrence by ctDNA and computed tomography (CT) scanning, dashed lines indicate mean time of recurrence based on CT (13.70 months) and ctDNA (8.69 months). (N = 19, Student’s t test)