Efficacy of liquid biopsy in colorectal cancer

Standard medical treatments have been established for postoperative adjuvant chemotherapy for colorectal cancer (CRC), as have front-line treatments for unresectable CRC (1,2). Several subtypes of CRC based on genes, gene mutations, and gene expression (3) have been reported. In recent years, comprehensive genome profiling (CGP) using a next-generation sequencer (NGS) has revealed prognostic factors, drug sensitivity factors, and resistance factors and has been shown to be applicable to the selection of treatment options. Traditionally, tumor specimens have been used for CGP testing, but liquid biopsy, which uses blood or other body fluids to diagnose the condition of tumors without directly collecting tumor tissue, is becoming more common. A certain amount of free DNA is normally present in human blood, and it is well known that the amount increases in cancer patients. DNA in plasma is called cell-free DNA (cfDNA). cfDNA is possibly derived from normal cells and tumors. cfDNA derived from tumors in cancer patients is known as circulating tumor DNA (ctDNA). Genetic testing using ctDNA is expected to be effective in various situations of treatment for CRC as a minimally invasive procedure to detect or monitor genetic abnormalities in tumors in real time. In other words, ctDNA gene panel testing (hereinafter referred to as liquid biopsy) for detecting minimal residual disease (MRD) in patients after the curative resection of CRC is thought to be useful for identifying patients at high risk of recurrence (4). In addition, liquid biopsy for patients with unresectable CRC may reveal drug sensitivity or resistance and be applicable to treatment selection (5). Sanz-Garcia et al.’s paper (6) is noteworthy, as it studies the efficacy of liquid biopsy in oligometastatic CRC after definitive therapy, which is considered to be between resectable and unresectable CRC.

Liquid biopsy for resectable colon cancer

Tie et al. reported that out of 178 patients without any adjuvant chemotherapy in a total population of 231 patients with stage II colon cancer, 14 patients in whom mutant alleles were detected in ctDNA 4 to 7 weeks after curative resection had a high recurrence rate [hazard ratio (HR) 18, 95% confidence interval (CI): 7.9–40, P<0.001], and that in 85% of these patients, mutant alleles were detected in ctDNA before recurrence was confirmed by imaging (7). Similarly, in 37 patients with curative resection of liver metastases, the 3-year recurrence-free survival rate was 0% in the mutant allele-positive group, which was significantly different from 84% in the mutation-negative group (HR 13, P<0.001). Reinert et al. studied 130 patients with stage I–III colon cancer who were performed curative resection. They found that the rate of recurrence was significantly higher in patients with ctDNA-positive than those without (HR 7.2, P<0.001) (8). The COSMOS-CRC-01 study reported the interim analysis results for stage II to III cases (9), and the 1-year disease-free survival (DFS) rate for ctDNA-negative cases at 28 days after surgery was 93.9%, while that for positive cases was 81.2%. The average period from the time at which postoperative ctDNA became positive to the confirmation of recurrence by imaging was 6.6 months. It was also reported in GALAXY study that cases with positive ctDNA at 4 weeks had a high risk of recurrence (HR 10.9, P<0.001). In GALAXY study, it is shown in a multivariate analysis of factors related to recurrence that ctDNA positivity at 4 weeks was the most powerful predictor of recurrence, rather than tumor (T)/lymph node (N) stage or RAS/BRAF mutation in stage II/III cases (10). Looking at the changes from weeks 4 to 12 after surgery, even if ctDNA was positive at 4 weeks, if it became negative at 12 weeks, the DFS was identical to that of the negative group at both time points. DFS did not differ in the ctDNA-negative group at 4 weeks, regardless of whether or not they received adjuvant chemotherapy (HR 1.3, P=0.63). Currently, there are many trials that are aiming to select adjuvant chemotherapy according to the status of postoperative ctDNA.

Liquid biopsy for unresectable or metastatic CRC

The results of the PERADIGM study showed that modified fluorouracil, l-leucovorin, and oxaliplatinm (mFOLFOX6) + panitumumab therapy significantly prolonged overall survival (OS) compared with mFOLFOX6 + bevacizumab therapy for RAS wild-type unresectable left-side CRC (1). In a biomarker study using liquid biopsy in the PARADIGM study (5), KRAS, NRAS, PTEN, and extracellular domain EGFR mutations; HER2 and MET amplifications; and ALK, RET, and NTRK1 fusions were analyzed. OS was prolonged with panitumumab arm versus bevacizumab arm in patients with ctDNA that lacked gene alterations in the panel (that is, negatively hyperselected; median in the overall population was 40.7 versus 34.4 months; HR 0.76) but was similar or inferior to panitumumab in patients with ctDNA that contained some level of gene alteration in the panel (19.2 versus 22.2 months; HR 1.13), regardless of tumor sidedness. These results suggest that negative hyperselection using ctDNA may guide optimal treatment selection in patients with mCRC. Furthermore, in the PARADIGM study, we demonstrated that gene alterations that occurred in certain cell signaling pathways were linked with shorter survival after disease progression, as observed through liquid biopsy after the completion of frontline chemotherapy (post-progression survival) and from the start of first-line treatment (OS) in patients with metastatic CRC (11). RTK/RAS gene pathway alterations were associated with shorter survival after panitumumab treatment. CPG island methylator phenotype (CIMP) pathway alterations were linked to shorter survival after bevacizumab treatment. These findings may help to guide subsequent treatment strategies for patients with metastatic CRC. It has been reported that the amount of ctDNA before the start of chemotherapy is a prognostic factor (12). In a meta-analysis of 1,076 CRC patients, patients with high level of pretreatment cfDNA had a significantly poorer prognosis (HR 2.39, P<0.001) (13). In addition, many reports have suggested that a decrease in ctDNA early after treatment is a useful predictor of early treatment efficacy. It is reported that of 52 cases of CRC with mutant alleles in tumor tissue, ctDNA was detected before the start of treatment in 48 cases (92.3%) and that the decrease in ctDNA early in the treatment period correlated with the effect of the treatment (14). Thus, liquid biopsy was expected to make it possible to predict the effect of chemotherapy.

Efficacy of liquid biopsy suggested by this article (6)

The originality and noteworthy aspect of this paper is that it examined the effectiveness of liquid biopsy in oligometastatic CRC (fewer than three metastatic lesions) after definitive therapy, which is considered to be between curatively resectable and unresectable CRC. It is widely known that the prognosis of oligometastatic lesions in CRC is extended by the resection of metastatic lesions (15). In this paper (6), liquid biopsy was performed before and after curative intent through surgery or radiation in 19 cases of oligometastatic CRC. Patients without ctDNA detection in post-treatment period were associated with longer OS (HR 11.28) and tended to show longer DFS (HR 2.97). Patients with persistently negative ctDNA had similar outcomes to those whose ctDNA was cleared.

The following points are limitations of this paper:

• As this research was conducted with a very limited number of cases, it is difficult to draw a definite conclusion. Multivariate analysis would also be impossible. Chemotherapy regimens were not described. It seems meaningless to further divide the limited number of cases into more groups.
• Various types of metastatic sites are included. Prognosis after the resection of liver or lung metastasis is acceptable, and the therapeutic effect of local therapy (surgery or radiation) clearly differs depending on the metastatic site. Therefore, these cannot be analyzed in the same way.

However, this study uniquely demonstrates that patients treated with curative intent through intervention, such as surgery or radiation, for oligometastasis showed worse survival if ctDNA is positive after treatment but not prior to the treatment. This paper can act as a basis for considerations in similar studies that will be conducted in the future (e.g., patient’s clinicopathological background, metastatic organs, treatment regimens, etc.) as well as an example of the effectiveness of liquid biopsy.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Journal of Gastrointestinal Oncology. The article did not undergo external peer review.

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jgo.amegroups.com/article/view/10.21037/jgo-2025-268/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Watanabe J, Muro K, Shitara K, et al. Panitumumab vs Bevacizumab Added to Standard First-line Chemotherapy and Overall Survival Among Patients With RAS Wild-type, Left-Sided Metastatic Colorectal Cancer: A Randomized Clinical Trial. JAMA 2023;329:1271-82. [Crossref] [PubMed]
2. Teranishi N, Uetake H. The Current Status of Adjuvant Chemotherapy for Colorectal Cancer in Japan: A Paradigm Shift from Oral Fluoropyridine Single Therapy to the Oxaliplatin Regimen. Cancers (Basel) 2025;17:518. [Crossref] [PubMed]
3. Guinney J, Dienstmann R, Wang X, et al. The consensus molecular subtypes of colorectal cancer. Nat Med 2015;21:1350-6. [Crossref] [PubMed]
4. Parikh AR, Van Seventer EE, Siravegna G, et al. Minimal Residual Disease Detection using a Plasma-only Circulating Tumor DNA Assay in Patients with Colorectal Cancer. Clin Cancer Res 2021;27:5586-94. [Crossref] [PubMed]
5. Shitara K, Muro K, Watanabe J, et al. Baseline ctDNA gene alterations as a biomarker of survival after panitumumab and chemotherapy in metastatic colorectal cancer. Nat Med 2024;30:730-9. [Crossref] [PubMed]
6. Sanz-Garcia E, Peinado P, Peláez A, et al. Circulating tumor DNA using a plasma-only assay predicts survival in patients with oligometastatic colorectal cancer after definitive therapy. J Gastrointest Oncol 2025;16:580-90. [Crossref] [PubMed]
7. Tie J, Wang Y, Tomasetti C, et al. Circulating tumor DNA analysis detects minimal residual disease and predicts recurrence in patients with stage II colon cancer. Sci Transl Med 2016;8:346ra92. [Crossref] [PubMed]
8. Reinert T, Henriksen TV, Christensen E, et al. Analysis of Plasma Cell-Free DNA by Ultradeep Sequencing in Patients With Stages I to III Colorectal Cancer. JAMA Oncol 2019;5:1124-31. [Crossref] [PubMed]
9. Tsukada Y, Matsuhashi N, Murano T, et al. Impact of postoperative integrated genomic and epigenomic signatures of circulating tumor DNA (ctDNA) on recurrence in resected colorectal cancer: Initial report of a prospective ctDNA monitoring study COSMOS-CRC-01. J Clin Oncol 2022;40:abstr 168.
10. Kotaka M, Shirasu H, Watanabe J, et al. Association of circulating tumor DNA dynamics with clinical outcomes in the adjuvant setting for patients with colorectal cancer from an observational GALAXY study in CIRCULATE-Japan. J Clin Oncol 2022;40:abstr 9.
11. Uetake H, Yamashita R, Shitara K, et al. Acquired gene alteration patterns and post-progression survival: PARADIGM study analysis. J Clin Oncol 2024;42:abstr 3507.
12. El Messaoudi S, Mouliere F, Du Manoir S, et al. Circulating DNA as a Strong Multimarker Prognostic Tool for Metastatic Colorectal Cancer Patient Management Care. Clin Cancer Res 2016;22:3067-77. [Crossref] [PubMed]
13. Spindler KG, Boysen AK, Pallisgård N, et al. Cell-Free DNA in Metastatic Colorectal Cancer: A Systematic Review and Meta-Analysis. Oncologist 2017;22:1049-55. [Crossref] [PubMed]
14. Tie J, Kinde I, Wang Y, et al. Circulating tumor DNA as an early marker of therapeutic response in patients with metastatic colorectal cancer. Ann Oncol 2015;26:1715-22. [Crossref] [PubMed]
15. Uetake H, Yasuno M, Ishiguro M, et al. A multicenter phase II trial of mFOLFOX6 plus bevacizumab to treat liver-only metastases of colorectal cancer that are unsuitable for upfront resection (TRICC0808). Ann Surg Oncol 2015;22:908-15. [Crossref] [PubMed]