Circulating tumor DNA (ctDNA) as a minimal residual disease (MRD) assessment and recurrence risk in patients undergoing curative intent resection with or without adjuvant chemotherapy in colorectal cancer: A systematic review and meta-analysis.

Abstract

3623 Background: Minimal residual disease (MRD) assessment may effectively detect cure in patients with colorectal cancer (CRC). Emerging data have suggested that circulating tumor DNA (ctDNA) can be a reliable biomarker for MRD in patients. Recent studies have shown the ability to detect MRD using ctDNA assay to assess recurrence risk and patient selection for adjuvant chemotherapy. We performed a systematic review and metanalysis of post operative ctDNA in Stage I-IV (oligometastatic) CRC patients after curative intent resection with or without adjuvant chemotherapy. Methods: We searched PubMed/Medline, EMBASE, Web of Science, Cochrane Library, and Google from inception to February 3, 2022 using keywords related to colorectal cancer, ctDNA, and MRD. The search also includes paper and conference presentations. The search resulted in 427 studies after removing the duplicates. Data were extracted to perform a meta-analysis using RevMan 5.4. software. Subsequent subgroup analysis was performed for stages I-III and oligometastatic stage IV CRC patients. Results: After the initial abstract screening, 48 studies were identified. The final review led to the inclusion of 27 studies representing 3459 patients with evaluable ctDNA, with 623 having +ve post-surgery ctDNA levels. Seven studies had analyses of patients specifically with oligometastatic disease, the rest 20 studies subdivided within stages I-III. The pooled HR for RFS in post-surgical ctDNA +ve vs -ve patients in all stages was 7.16 (95% CI 6.12-8.36) p <0.00001. Subgroup analysis revealed pooled HR = 8.27 (95% CI 6.16-11.09) and 6.07 (95% CI 4.54-8.13) for stage I-III and IV CRC, respectively. Only 11 studies did analysis for post adjuvant chemotherapy patients based on ctDNA status. The pooled HR for RFS in post-adjuvant chemotherapy ctDNA +ve versus -ve patients in all stages was 12.40 (95% CI 9.24-16.64) p <0.00001. Subgroup analysis revealed pooled HR = 13.95 (95% CI 9.08-21.43) and 11.39 (95% CI 5.99-21.66) for stage I-III and IV CRC, respectively. Conclusions: This is the largest and most current meta-analysis done on ctDNA levels as MRD assessment in CRC. Our analysis emphasizes that post operative ctDNA is a strong prognostic marker of RFS. Based on our results ctDNA can be a significant and independent predictor of RFS. Several ctDNA-based randomized adjuvant trials are ongoing internationally to confirm the clinical utility of ctDNA in colorectal cancer. [Table: see text]