Liquid Biopsy for Prognosis and Treatment in Metastatic Colorectal Cancer: Circulating Tumor Cells vs Circulating Tumor DNA

Negative Hyperselection in Metastatic Colorectal Cancer for First-Line Anti-EGFR Therapy: A Narrative Review

Colorectal cancer (CRC) remains a leading cause of cancer-related mortality, with metastatic disease posing significant therapeutic challenges. While anti-EGFR therapy has improved outcomes for patients with RAS and BRAF wild-type tumors, resistance remains a major hurdle, limiting treatment efficacy. The concept of negative hyperselection has emerged as a refinement of molecular profiling, identifying additional genomic alterations-such as HER2 and MET amplificationsand MAP2K1 mutations-that predict resistance to anti-EGFR agents. Studies incorporating these expanded assessments have demonstrated that nearly half of patients with RAS/BRAF wild-type tumors harbor alternative resistance biomarkers, underscoring the need for expanded selection criteria. Liquid biopsies, particularly circulating tumor DNA (ctDNA) analysis, have revolutionized precision oncology by providing a minimally invasive, real-time assessment of tumor dynamics. ctDNA-based hyperselection enables the detection of resistance-associated alterations, guiding treatment decisions with greater accuracy than conventional tissue biopsies. Recent trials support the predictive value of ctDNA-defined negative hyperselection, revealing superior outcomes for patients stratified through liquid biopsy. This narrative review explores the evolving role of molecular hyperselection in first-line anti-EGFR therapy, emphasizing the integration of ctDNA to refine patient selection, enhance therapeutic efficacy, and pave the way for personalized treatment strategies in metastatic CRC.

Clinical implications of Alu-based cell-free DNA and serum onco-piRNA monitoring in colorectal cancer management

BACKGROUND

Colorectal cancer (CRC) remains a significant global health challenge, characterized by high morbidity and mortality rates. This study explores the potential of Alu-based cell-free DNA (cfDNA) and specific PIWI-interacting RNAs (piRNAs) as innovative biomarkers for monitoring treatment responses in CRC patients.

METHODS

We analyzed plasma samples from 70 CRC patients, equally divided between those undergoing chemotherapy and surgical interventions.

RESULTS

Our findings reveal that certain piRNAs, particularly piRNA-823, piRNA-54265, and piRNA-1245, exhibit significant prognostic value, with notable expression changes observed in the chemotherapy group compared to the surgery group. Furthermore, the levels of ALU-based cfDNA fragments showed a marked decrease post-chemotherapy, suggesting their utility in assessing therapeutic efficacy.

CONCLUSIONS

This research underscores the importance of integrating these molecular tools particularly piRNA-823 and ALU-based cfDNA into clinical practice, potentially enhancing the management strategies for CRC patients and improving their outcomes.

CTCs and liquid biopsies in patients with colorectal cancer

Liquid biopsy, which includes both circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs) has become a valuable tool for cancer diagnosis and monitoring. It offers a less invasive approach than traditional tissue biopsy and recent technological advancements have enabled their use in comprehensive analysis of tumor molecular characteristics. By capturing the dynamic nature of tumors through repeated sampling, liquid biopsy addresses the limitations of tissue biopsy and provides insights into tumor heterogeneity over time. It is being extensively studied in patients with advanced colorectal cancer because it can aid in diagnosis, predict disease course, and guide treatment selection. Furthermore, as personalized medicine becomes more common, identifying genetic changes that cause cancer cells to become resistant to treatment is crucial. This chapter explores the emerging field of liquid biopsy, with a particular focus on the role and potential of circulating tumor cells (CTCs) in the context of colorectal cancer.

Circulating tumor DNA as a predictive biomarker for treatment response and survival in metastatic colorectal cancer

PURPOSE

To explore the potential of circulating tumor DNA (ctDNA) as a prognostic biomarker to predict treatment response and survival outcomes in patients with metastatic colorectal cancer (mCRC).

METHODS

A retrospective analysis was conducted on 134 patients with mCRC who were treated between January 2020 and December 2021. The patients were classified into ctDNA-negative and ctDNA-positive groups based on plasma ctDNA detection. Demographic, clinical, and laboratory parameters, treatment response, survival outcomes, and adverse events were recorded and analyzed.

RESULTS

No significant differences were observed in baseline characteristics between the two groups. Compared to the ctDNA-positive patients, ctDNA-negative patients exhibited superior outcomes, including a higher objective response rate (65.22% vs. 46.15%), disease control rate (81.16% vs. 63.08%), progression-free survival (8.24 ± 1.02 vs. 7.86 ± 0.91 months), overall survival (24.58 ± 3.58 vs. 23.27 ± 3.46 months), and 1-year survival rate (73.91% vs. 55.38%). The ctDNA-positive group had a significantly higher incidence of adverse events. Correlation analyses revealed significant associations between ctDNA status, tumor markers, treatment response, and survival outcomes.

CONCLUSIONS

ctDNA is a promising noninvasive biomarker for predicting treatment response, survival, and adverse events in mCRC, potentially guiding personalized therapeutic strategies.

Ongoing Clinical Trials and Future Research Scenarios of Circulating Tumor DNA for the Treatment of Metastatic Colorectal Cancer

Liquid biopsy using circulating tumor DNA (ctDNA) has emerged as a minimally invasive, timely approach to provide molecular diagnosis and monitor tumor evolution in patients with cancer. Since the molecular landscape of metastatic colorectal cancer (mCRC) is substantially heterogeneous and dynamic over space and time, ctDNA holds significant advantages as a biomarker for this disease. Numerous studies have demonstrated that ctDNA broadly recapitulates the molecular profile of the primary tumor and metastases, and have mainly focused on the genotyping of RAS and BRAF, that is propaedeutic for anti-EGFR treatment selection. However, ctDNA soon broadened its scope towards the assessment of early tumor response, as well as the identification of drug resistance biomarkers to drive potential molecular actionability. In this review article, we provide an overview of the current state-of-the-art of this methodology and its applications, focusing on ongoing clinical trials that employ ctDNA to prospectively guide treatment in patients with mCRC.

Diagnostic and prognostic significance of ALU-based cell-free DNA in colorectal cancer: a systematic review and meta-analysis

Introduction

Colorectal cancer (CRC) is a major global health concern. This study aimed to investigate the role of ALU-based cell-free DNA (cfDNA) in the diagnosis and prognosis of CRC.

Methods

We selected relevant literature from PubMed, Scopus, Web of Science, EMBASE, and Science Direct databases based on strict inclusion and exclusion criteria. 17 eligible studies were included in the final analysis (13 studies for diagnostic and 4 studies for prognostic meta-analysis). The search covered relevant publications up to July 1, 2024.

Results

The pooled sensitivity, specificity, and diagnostic odds ratios (DOR) of ALU-based cfDNA in CRC diagnosis were 0.81 (95% CI= [0.70, 0.89]), 0.90 (95% CI= [0.70, 0.96]), and 40.58 (95% CI= [17.87, 92.19]), respectively. The area under the ROC curve was 0.92 (95% CI= [0.89, 0.94]). Patients with higher concentrations of plasma/serum ALU-based cfDNA had poorer overall survival (OS) (pooled hazard ratio = 2.33 ([95% CI= [1.80, 3.03]).

Conclusion

The current evidence supports the utility of circulating ALU as a promising non-invasive diagnostic and prognostic tool for CRC. Furthermore, as a potential biomarker, ALU-based cfDNA could play a significant role in clinical application.

Clinical implications

The evidence suggests that circulating ALU-based cell-free DNA (cfDNA) holds promise as a non-invasive diagnostic and prognostic tool for colorectal cancer, potentially enhancing clinical decision-making.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier PROSPERO (CRD42023486369).

Temporal dynamics of RAS mutations in circulating tumor DNA in metastatic colorectal cancer: clinical significance of mutation loss during treatment

PURPOSE

In metastatic colorectal cancer (mCRC), RAS mutation loss may occur during the standard-of-care regimen. In this study, we aimed to investigate the temporal dynamics of the RAS gene and its clinical significance.

METHODS

This was a retrospective, single-center study that included 82 patients with tissue RAS-mutant (RAS-MT) mCRC who underwent circulating tumor DNA (ctDNA) RAS monitoring between January, 2013-April, 2023. Patients were analyzed for the rate of change over time to acquired RAS mutation loss (aRAS-ML) and clinicopathological factors. The prognostic relevance of mutation loss was assessed.

RESULTS

aRAS-ML was detected in 33 (40.2%) patients, 32 of whom had a mutation loss in the first ctDNA RAS assay. Patients with a RAS mutation detected in the first assay had a median time of 8 months until the second ctDNA RAS assay, with 4.5% cases newly converted to aRAS-ML; no new conversions were detected at the third assay. The aRAS-ML group exhibited more single-organ metastases in the target organ during ctDNA measurement (aRAS-ML: 84.8% vs. RAS-MT: 59.2%, p = 0.02). Of the 33 patients with aRAS-ML, seven (21.2%) received anti-epidermal growth factor receptor (EGFR) therapy, with a median progression-free survival of 8 months. Multivariate analysis revealed that persistent ctDNA RAS mutation was an independent prognostic factor for overall survival (hazard ratio: 2.7, 95% confidence interval: 1.1-6.3, p = 0.02).

CONCLUSION

The rate of ctDNA mutation loss in patients with RAS-MT mCRC decreases over time. Therefore, using a ctDNA RAS assay early in treatment will assist in challenging the use of EGFR regimens.

Colorectal Cancer: Genetic Underpinning and Molecular Therapeutics for Precision Medicine

Colorectal cancer (CRC) accounts for about 10% of all cancer cases and 9% of cancer-related deaths globally. In the United States alone, CRC represents approximately 12.6% of all cancer cases, with a mortality rate of about 8%. CRC is now the first leading cause of cancer death in men younger than age 50 and second in women younger than age 50. This review delves into the genetic landscape of CRC, highlighting key mutations and their implications in disease progression and treatment. We provide an overview of the current and emerging therapeutic strategies tailored to individual genomic profiles.

Multimodal Treatment of Metastatic Rectal Cancer in a Young Patient: Case Report and Literature Review

Metastatic colorectal cancer requires a multidisciplinary and individualized approach. Herein, we reported the case of a young woman diagnosed with metastatic rectal cancer who received an individualized multimodal treatment strategy that resulted in a remarkable survival. There were several particular aspects of this case, such as the early onset of the disease, the successful use of conversion therapy, the application of liquid biopsy to guide treatment, and the specific nature of the bone metastasis. To offer more insights for navigating such challenges in patients with metastatic colorectal cancer, we have conducted a literature review to find more data related to the particularities of this case. The incidence of early onset colorectal cancer is on the rise. Data suggests that it differs from older-onset colorectal cancer in terms of its pathological, epidemiological, anatomical, metabolic, and biological characteristics. Conversion therapy and surgical intervention provide an opportunity for cure and improve outcomes in metastatic colorectal cancer. It is important to approach each case individually, as every patient with limited liver disease should be considered as a candidate for secondary resection. Moreover, liquid biopsy has an important role in the individualized management of metastatic colorectal cancer patients, as it offers additional information for treatment decisions.

Circulating Tumor DNA to Drive Treatment in Metastatic Colorectal Cancer

In the evolving molecular treatment landscape of metastatic colorectal cancer (mCRC), the identification of druggable alterations is pivotal to achieve the best therapeutic opportunity for each patient. Because the number of actionable targets is expanding, there is the need to timely detect their presence or emergence to guide the choice of different available treatment options. Liquid biopsy, through the analysis of circulating tumor DNA (ctDNA), has proven safe and effective as a complementary method to address cancer evolution while overcoming the limitations of tissue biopsy. Even though data are accumulating regarding the potential for ctDNA-guided treatments applied to targeted agents, still major gaps in knowledge exist as for their application to different areas of the continuum of care. In this review, we recapitulate how ctDNA information could be exploited to drive different targeted treatment strategies in mCRC patients, by refining molecular selection before treatment by addressing tumor heterogeneity beyond tumor tissue biopsy; longitudinally monitoring early-tumor response and resistance mechanisms to targeted agents, potentially leading to tailored, molecular-driven, therapeutic options; guiding the molecular triage towards rechallenge strategies with anti-EGFR agents, suggesting the best time for retreatment; and providing opportunities for an "enhanced rechallenge" through additional treatments or combos aimed at overcoming acquired resistance. Besides, we discuss future perspectives concerning the potential role of ctDNA to fine-tune investigational strategies such as immuno-oncology.

Dynamic Monitoring of Circulating Tumor DNA in Patients With Metastatic Colorectal Cancer

PURPOSE

Plasma circulating tumor DNA (ctDNA) is a valuable resource for tumor characterization and for monitoring of residual disease during treatment; however, it is not yet introduced in metastatic colorectal cancer (mCRC) routine clinical practice. In this retrospective exploratory study, we evaluated the role of ctDNA in patients with mCRC treated with chemotherapy plus bevacizumab.

MATERIALS AND METHODS

Fifty-three patients were characterized for RAS and BRAF status on tumor tissue before the start of treatment. Plasma was collected at baseline, at first clinical evaluation, and at disease progression. ctDNA analysis was performed using Oncomine Colon cfDNA Assay on the Ion S5 XL instrument.

RESULTS

At baseline, from a plasma sample, RAS, BRAF, or PIK3CA mutations were detected in 44 patients. A high correspondence was observed between ctDNA and tumor tissue mutations (KRAS 100%, NRAS 97.9%, BRAF 97.9%, PIK3CA 90%). Low baseline variant allele frequency (VAF) was found to be associated with longer median progression-free survival (PFS) compared with those with high VAF (15.9 v 12.2 months, P = .02). A higher PFS {12.29 months (95% CI, 9.03 to 17.9) v 8.15 months (95% CI, 2.76 to not available [NA]), P = .04} and overall survival (34.1 months [95% CI, 21.68 to NA] v 11.1 months [95% CI, 3.71 to NA], P = .003) were observed in patients with large decline in VAF at first evaluation.

CONCLUSION

ctDNA analysis is useful for molecular characterization and tumor response monitoring in patients with mCRC. Quantitative variations of released ctDNA are associated with clinical outcomes.

Ibero-American Consensus Review and Incorporation of New Biomarkers for Clinical Practice in Colorectal Cancer

Advances in genomic technologies have significantly improved the management of colorectal cancer (CRC). Several biomarkers have been identified in CRC that enable personalization in the use of biologic agents that have shown to enhance the clinical outcomes of patients. However, technologies used for their determination generate massive amounts of information that can be difficult for the clinician to interpret and use adequately. Through several discussion meetings, a group of oncology experts from Spain and several Latin American countries reviewed the latest literature to provide practical recommendations on the determination of biomarkers in CRC based on their clinical experience. The article also describes the importance of looking for additional prognostic biomarkers and the use of histopathology to establish an adequate molecular classification. Present and future of immunotherapy biomarkers in CRC patients are also discussed, together with several techniques for marker determination, including liquid biopsy, next-generation sequencing (NGS), polymerase chain reaction (PCR), and fecal immunohistochemical tests. Finally, the role of Molecular Tumor Boards in the diagnosis and treatment of CRC is described. All of this information will allow us to highlight the importance of biomarker determination in CRC.

Current Status of Circulating Tumor Cells in Head and Neck Squamous Cell Carcinoma: A Review

OBJECTIVE

Circulating tumor cells (CTCs) are found in the blood of patients with cancer, including head and neck squamous cell carcinomas (HNSCCs). The aim is to review the most up-to-date status of CTCs for applications in patients with HNSCC.

DATA SOURCES

English articles in PubMed.

REVIEW METHODS

All the studies on CTCs in HNSCCs in the literature were reviewed.

CONCLUSIONS

There is emerging information on the diagnostic and prognostic value of CTCs in HNSCCs. Evidence also highlights the advantages of various downstream analysis approaches over circulating tumor DNA (ctDNA), such as single-CTC analysis, ex vivo, and in vivo expansion of CTCs. Multiple phenotypic surface markers (cytokeratins, EpCAM, vimentin, etc.), used for CTCs characterization using different immunoassays, could predict disease progression as well as patients' response to treatment efficacy. Immune checkpoint inhibitors' status in CTCs could also provide better insight into treatment. Clonal expansion of CTCs and single-cell analysis of CTCs are the most emerging fields nowadays which may offer an understanding of the mechanism of tumor evolution as well as therapeutic efficacy. Although several clinical trials are ongoing, limitations still exist in the detection and characterization of CTCs. Due to the lack of a gold standard protocol, the sensitivity and specificity of CTC enumeration methods vary.

IMPLICATIONS FOR PRACTICE

Prospective clinical trials are still needed before CTCs can be employed as diagnostic and prognostic markers in the clinical management of patients with HNSCC.

Current concepts of anti-EGFR targeting in metastatic colorectal cancer

Anti-EGFR targeting is one of the key strategies in the treatment of metastatic colorectal cancer (mCRC). For almost two decades oncologists have struggled to implement EGFR antibodies in the mCRC continuum of care. Both sidedness and RAS mutational status rank high among the predictive factors for the clinical efficacy of EGFR inhibitors. A prospective phase III trial has recently confirmed that anti-EGFR targeting confers an overall survival benefit only in left sided RAS-wildtype tumors when given in first line. It is a matter of discussion if more clinical benefit can be reached by considering putative primary resistance mechanisms (e.g., HER2, BRAF, PIK3CA, etc.) at this early stage of treatment. The value of this procedure in daily routine clinical utility has not yet been clearly delineated. Re-exposure to EGFR antibodies becomes increasingly crucial in the disease journey of mCRC. Yet re- induction or re-challenge strategies have been problematic as they relied on mathematical models that described the timely decay of EGFR antibody resistant clones. The advent of liquid biopsy and the implementation of more accurate next-generation sequencing (NGS) based high throughput methods allows for tracing of EGFR resistant clones in real time. These displays the spatiotemporal heterogeneity of metastatic disease compared to the former standard radiographic assessment and re-biopsy. These techniques may move EGFR inhibition in mCRC into the area of precision medicine in order to apply EGFR antibodies with the increase or decrease of EGFR resistant clones. This review critically discusses established concepts of tackling the EGFR pathway in mCRC and provides insight into the growing field of liquid biopsy guided personalized approaches of EGFR inhibition in mCRC.

Application of histology-agnostic treatments in metastatic colorectal cancer

Cancer treatment is increasingly focused on targeting molecular alterations identified across different tumor histologies. While some oncogenic drivers such as microsatellite instability (MSI) and NTRK fusions are actionable with the very same approach regardless of tumor type ("histology-agnostic"), others require histology-specific therapeutic adjustment ("histology-tuned") by means of adopting specific inhibitors and ad hoc combinations. Among histology-agnostic therapies, pembrolizumab or dostarlimab demonstrated comparable activity in MSI metastatic colorectal cancer (mCRC) as in other tumors with MSI status (ORR 38% vs 40% and 36% vs 39%, respectively), while entrectinib or larotrectinib proved effective in NTRK rearranged mCRC even though less dramatically than in the overall population (ORR 20% vs 57%, and 50% vs 78%, respectively). Histology-tuned approaches in mCRC are those targeting BRAF^V600E mutations and ERBB2 amplification, highlighting the need of simultaneous anti-EGFR blockade or careful choice of companion inhibitors in this tumor type. Anti-RET and anti-ALK therapies emerged as a potential histology-agnostic indications, while anti-KRAS^G12C strategies could develop as future histology-tuned therapies. Targeting of ERBB2 mutations and NRG1 fusion provided discrepant results. In conclusion, agnostic targets such as MSI and NTRK fusions are already exploitable in mCRC, while the plethora of emerging histology-tuned targets represent a challenging opportunity requiring concurrent evolution of molecular diagnostic tools.

Liquid Biopsies in Colorectal Liver Metastases: Towards the Era of Precision Oncologic Surgery

Tumor mutational analysis has been incorporated into the management of patients with CRLM since it can provide valuable prognostic information as well as guide peri-operative systemic treatment. Unlike tumor biopsy, liquid biopsy has emerged as a promising, non-invasive alternative that can detect cell-derived markers from a variety of body fluids and might better characterize all subclones present at a specific time point and allow sequential monitoring of disease evolution. Although not currently considered standard of care, an increasing number of cancer centers are nowadays routinely using liquid biopsies in the treatment of CRLM patients with promising results. The current review provides an overview of liquid biopsies in cancer therapeutics and focuses on the application of this relatively new approach on patients with CRLM.

Liquid biopsies to monitor and direct cancer treatment in colorectal cancer

Colorectal cancer (CRC) is one of the most prevalent and deadly cancers worldwide. Despite recent improvements in treatment and prevention, most of the current therapeutic options are weighted by side effects impacting patients' quality of life. Better patient selection towards systemic treatments represents an unmet clinical need. The recent multidisciplinary and molecular advancements in the treatment of CRC patients demand the identification of efficient biomarkers allowing to personalise patient care. Currently, core tumour biopsy specimens represent the gold-standard biological tissue to identify such biomarkers. However, technical feasibility, tumour heterogeneity and cancer evolution are major limitations of this single-snapshot approach. Genotyping circulating tumour DNA (ctDNA) has been addressed as potentially overcoming such limitations. Indeed, ctDNA has been retrospectively demonstrated capable of identifying minimal residual disease post-surgery and post-adjuvant treatment, as well as spotting druggable molecular alterations for tailoring treatments in metastatic disease. In this review, we summarise the available evidence on ctDNA applicability in CRC. Then, we review ongoing clinical trials assessing how liquid biopsy can be used interventionally to guide therapeutic choice in localised, locally advanced and metastatic CRC. Finally, we discuss how its widespread could transform CRC patients' management, dissecting its limitations while suggesting improvement strategies.

Clinical management of metastatic colorectal cancer in the era of precision medicine

Colorectal cancer (CRC) represents approximately 10% of all cancers and is the second most common cause of cancer deaths. Initial clinical presentation as metastatic CRC (mCRC) occurs in approximately 20% of patients. Moreover, up to 50% of patients with localized disease eventually develop metastases. Appropriate clinical management of these patients is still a challenging medical issue. Major efforts have been made to unveil the molecular landscape of mCRC. This has resulted in the identification of several druggable tumor molecular targets with the aim of developing personalized treatments for each patient. This review summarizes the improvements in the clinical management of patients with mCRC in the emerging era of precision medicine. In fact, molecular stratification, on which the current treatment algorithm for mCRC is based, although it does not completely represent the complexity of this disease, has been the first significant step toward clinically informative genetic profiling for implementing more effective therapeutic approaches. This has resulted in a clinically relevant increase in mCRC disease control and patient survival. The next steps in the clinical management of mCRC will be to integrate the comprehensive knowledge of tumor gene alterations, of tumor and microenvironment gene and protein expression profiling, of host immune competence as well as the application of the resulting dynamic changes to a precision medicine-based continuum of care for each patient. This approach could result in the identification of individual prognostic and predictive parameters, which could help the clinician in choosing the most appropriate therapeutic program(s) throughout the entire disease journey for each patient with mCRC. CA Cancer J Clin. 2022;72:000-000.

Clinical Characteristics of Metastatic Colorectal Cancer Combined with Gastrointestinal Perforation and Prognostic Value of Circulating Tumor DNA

Objective

To explore the clinical characteristics of metastatic colorectal cancer combined with gastrointestinal perforation and the prognostic value of circulating tumor DNA (ctDNA).

Methods

A total of 97 patients with metastatic colorectal cancer and gastrointestinal perforation were enrolled as the research objects between February 2016 and January 2019. Their clinicopathological characteristics were statistically analyzed. Patients were divided into the death group (n = 78) and the survival group (n = 19) according to their survival status at 3 years after surgery. The ctDNA level between the two groups was compared. Also, its evaluation value on patient prognosis was analyzed. The survival time in patients with different levels of ctDNA was compared.

Results

The clinical staging was stage T4 in patients with metastatic colorectal cancer combined with gastrointestinal perforation, including 70 cases (72.16%) aged ≥60 years and 27 cases (27.84%) <60 years. There were 61 males (62.89%) and 36 females (37.11%). There were 27 cases (27.84%) with primary site at left colon, 59 cases (60.82%) at right colon and 11 cases (11.34%) at rectum. There were 56 cases (57.73%) with number of metastatic organs ≥2 and 41 cases (42.27%) <2. There were 58 cases (59.79%) treated with VEGF inhibitor before perforation, 40 cases (41.24%) with lung metastasis, 72 cases (74.23%) with liver metastasis, 30 cases (30.93%) with pelvic metastasis, 24 cases (24.74%) with distant lymph node metastasis, 56 cases (57.73%) with obstruction, and 35 cases (36.08%) with diverticulum. According to survival status at 3 years after after surgery, patients were divided into the death group (n = 78) and the survival group (n = 19). The level of plasma ctDNA in the death group was higher than that in the survival group (P < 0.05). The area under curve (AUC) of ctDNA for predicting survival of patients was 0.806. According to ctDNA expression, patients were divided into the high expression group (n = 57) and the low expression group (n = 40). The survival rate in the high expression group was lower than that in the low expression group (7.02% (4/57) vs 36.38% (15/40)) (P < 0.001). The median survival time for the two groups was 18.20 and 28.10 months, respectively.

Conclusion

Clinical characteristics of metastatic colorectal cancer combined with gastrointestinal perforation include elderly age, obstruction, and diverticulum. The expression of ctDNA has evaluation value for prognosis of patients.

Clinical Impact of Primary Tumor Location in Metastatic Colorectal Cancer Patients Under Later-Line Regorafenib or Trifluridine/Tipiracil Treatment

Background

Primary tumor location (PTL) is an important prognostic and predictive factor in the first-line treatment of metastatic colorectal cancer (mCRC). Although regorafenib (REG) and trifluridine/tipiracil (FTD/TPI) have been introduced recently, the clinical impact of PTL in these treatments is not well understood.

Materials and Methods

We retrospectively evaluated patients with mCRC who were registered in a multicenter observational study (the REGOTAS study). The main inclusion criteria were Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-2, refractory or intolerant to fluoropyrimidines, oxaliplatin, irinotecan, angiogenesis inhibitors, anti-epidermal growth factor receptor therapy (if RAS wild-type), and no prior use of REG and FTD/TPI. The impact of PTL on overall survival (OS) was evaluated using Cox proportional hazard models based on baseline characteristics.

Results

A total of 550 patients (223 patients in the REG group and 327 patients in the FTD/TPI group) were included in this study, with 122 patients with right-sided tumors and 428 patients with left-sided tumors. Although the right-sided patients had significantly shorter OS compared with the left-sided patients by univariate analysis (p = 0.041), a multivariate analysis revealed that PTL was not an independent prognostic factor (hazard ratio, 0.95; p = 0.64). In a subgroup analysis, the OS was comparable between the REG and FTD/TPI groups regardless of PTL (p for interactions = 0.60).

Conclusions

In the present study, PTL is not a prognostic and predictive factor in patients with mCRC under later-line REG or FTD/TPI therapy.