Abstract
A circulating tumor DNA (ctDNA) assay (Signatera; Natera) has been marketed for use in the surveillance of resected colorectal cancer despite limited data supporting such practice. To compare a ctDNA assay with standard radiographic imaging and measurement of carcinoembryonic antigen (CEA) levels, per National Comprehensive Cancer Network guidelines, in the surveillance of resected colorectal cancer. This retrospective, single-center cohort study evaluated surveillance strategies of ctDNA, imaging, and measurement of CEA levels in patients with resected colorectal cancer from September 1, 2019, to November 30, 2021. The sensitivity and specificity of ctDNA, imaging, measurement of CEA levels, and combination of imaging plus measurement of CEA levels in detecting a confirmed recurrence of colorectal disease. A confirmed recurrence was defined as a positive ctDNA finding or a finding on imaging confirmed by biopsy, CEA level elevation, or subsequent tumor radiographic dynamics. A total of 48 patients with curatively resected colorectal cancer satisfied the inclusion criteria for this study (28 men [58.3%]; median age, 60 [IQR, 34-85] years) and underwent surveillance by ctDNA, imaging, and measurement of CEA levels. Fifteen patients had disease recurrence during surveillance. Positive ctDNA findings confirmed disease recurrence in 8 patients; imaging, in 9 patients; CEA levels, in 3 patients; and combined imaging plus CEA levels, in 11 patients. Numerically, ctDNA did not perform better than imaging in detecting recurrence, with sensitivities of 53.3% (95% CI, 27.4%-77.7%) and 60.0% (95% CI, 32.9%-82.5%), respectively (P > .99). The combination of imaging plus measurement of CEA levels (sensitivity, 73.3% [95% CI, 44.8%-91.1%]) had a numerical advantage compared with ctDNA in identifying recurrence (P = .55). In addition, no significant difference was noted among ctDNA (median, 14.3 months), imaging (median, 15.0 months), or imaging plus measurement of CEA levels (median, 15.0 months) in the time to identify disease recurrence. The findings of this cohort study suggest that ctDNA assay may not provide advantages as a surveillance strategy compared with standard imaging combined with CEA levels when performed per National Comprehensive Cancer Network guidelines.
Highlights
Surveillance strategies in the management of resected locoregional and metastatic colorectal cancer have been investigated thoroughly during the last several decades.[1-5]
The combination of imaging plus measurement of carcinoembryonic antigen (CEA) levels had a numerical advantage compared with circulating tumor DNA (ctDNA) in identifying recurrence (P = .55)
The findings of this cohort study suggest that ctDNA assay may not provide advantages as a surveillance strategy compared with standard imaging combined with CEA levels when performed per National Comprehensive Cancer Network guidelines
Summary
Surveillance strategies in the management of resected locoregional and metastatic colorectal cancer have been investigated thoroughly during the last several decades.[1-5]. Carcinoembryonic antigen (CEA) levels and intensive imaging have been investigated as sole or combination strategies in the surveillance of resected stage I to III disease, considerable disagreement remains regarding the impact of these assays on colorectal cancer outcome.[4,6,7]. The National Comprehensive Cancer Network (NCCN) currently recommends the surveillance of stage II and III colorectal cancer with measurement of CEA levels every 3 to 6 months for 2 years followed by every 6 months for 3 years. For resected stage IV disease, the NCCN recommends a similar CEA surveillance strategy and intensive imaging, with a CT scan of the chest, abdomen, and pelvis every 3 to 6 months for 2 years followed by every 6 to 12 months for another 3 years.[9]. Neither the NCCN nor the ESMO recommend the use of circulating tumor DNA (ctDNA) assays for surveillance of colorectal cancer
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