Metastatic colorectal cancer (mCRC) represents a complex and biologically diverse disease in which treatment decisions increasingly depend on molecular characteristics, disease burden, and patient-specific factors. While therapeutic options have expanded over recent years, treatment selection increasingly depends on molecular profile, tumour location, prior therapy, and patient fitness.
On April 14, 2026, Annals of Oncology published the updated ESMO Clinical Practice Guideline for the diagnosis, treatment, and follow-up of metastatic colorectal cancer, developed by Cremolini and colleagues on behalf of the ESMO Guidelines Committee.
Title: Metastatic colorectal cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up
Authors: C. Cremolini, M. Chalabi, E. Elez, M. Fassan, M. Gelli, D. Goéré, D.P. Modest, C. Montagut, P. Osterlund, J. Ricke, J. Seligmann, J. Taieb, T. Yoshino, L. Wyrwicz, M. Ducreux
Shifting Epidemiology of CRC
Colorectal cancer remains one of the leading causes of cancer-related mortality worldwide, ranking third globally. Increasing incidence rates, including a shift toward earlier-onset disease, have been partly linked to lifestyle-related factors such as obesity, physical inactivity, alcohol consumption, high intake of red meat, smoking, and alterations in the gut microbiota.
Recent data published in JAMA Oncology highlight concerning trends in younger patients. An analysis of U.S. mortality data from 1990 to 2023 showed that, despite an overall decline in cancer mortality among individuals younger than 50, colorectal cancer mortality increased by 1.1% annually since 2005 and became the leading cause of cancer-related death in this age group by 2023. In addition, nearly three-quarters of patients younger than 50 are diagnosed with advanced disease, indicating a high proportion of late-stage presentation at diagnosis.
A Framework Built on Molecular Precision
A central message of the guideline is the critical importance of early and comprehensive molecular profiling. At the time of diagnosis, all patients with mCRC should undergo testing for key biomarkers, including RAS (KRAS and NRAS), BRAF V600E, mismatch repair (MMR) or microsatellite instability (MSI) status, and HER2 alterations. These biomarkers are fundamental determinants of treatment selection.
The guideline also highlights the growing role of circulating tumor DNA (ctDNA), particularly in situations where tissue is unavailable or rapid decision-making is required. Importantly, molecular characterization should be performed promptly, with results ideally available within two weeks, ensuring that systemic therapy is initiated without delay.
Multidisciplinary Decision-Making from the Start
Another key principle is the early involvement of a multidisciplinary team. All patients should be discussed at diagnosis, integrating radiological, pathological, and molecular data to define the optimal treatment strategy. This approach is particularly relevant in patients with potentially resectable or oligometastatic disease, where treatment intent may shift from palliative to curative.
Staging relies on high-quality imaging, including contrast-enhanced CT of the chest, abdomen, and pelvis, with liver MRI recommended in selected cases. These assessments are not static; re-evaluation during treatment is essential, particularly when conversion to resectability is a goal.
Locoregional Therapy: A Curative Opportunity in Selected Patients
For a subset of patients, particularly those with limited metastatic spread, locoregional therapies remain a cornerstone of management. Surgical resection, ablation, or combined approaches may offer long-term disease control and, in some cases, cure.
The guideline emphasizes that systemic therapy is often the initial step, followed by reassessment for local treatment in cases of disease stabilization or response. In highly selected patients with liver-only unresectable disease, liver transplantation may be considered under strict criteria.
Read about ESMO Clinical Practice Guideline Express Update: Exercise and Survival in Localised Colon Cancer on OncoDaily.
First-Line Treatment: Biology Drives Strategy
First-line treatment in metastatic colorectal cancer not amenable to locoregional therapy is primarily determined by MMR/MSI status, followed by molecular profile, tumor location, and patient fitness.
For patients with dMMR or MSI-H tumors, immunotherapy is the preferred approach. Nivolumab plus ipilimumab is recommended, with pembrolizumab as an alternative.
For patients with pMMR or MSS disease, treatment depends on eligibility for combination chemotherapy and molecular characteristics.
Patients Eligible for Combination Chemotherapy
In fit patients, treatment is guided by RAS and BRAF status:
- RAS-mutated tumors: FOLFOXIRI plus bevacizumab can be recommended in selected patients, while doublet chemotherapy plus bevacizumab remains an alternative.
- BRAFV600E-mutated tumors: FOLFOX plus encorafenib and cetuximab is recommended. FOLFIRI plus encorafenib and cetuximab is also recommended, particularly in patients previously treated with oxaliplatin-based adjuvant therapy or with contraindications to oxaliplatin. If these regimens are not available, oxaliplatin-based doublet chemotherapy plus bevacizumab can be used, and FOLFOXIRI plus bevacizumab may be considered in selected patients with right-sided tumors.
- RAS-wild-type and BRAF-wild-type tumors: treatment is influenced by tumor sidedness. Left-sided tumors are preferentially treated with doublet chemotherapy plus anti-EGFR therapy, whereas right-sided tumors are more commonly managed with bevacizumab-based regimens.
Recent regulatory updates support this treatment approach. On February 24, 2026, the U.S. Food and Drug Administration granted full approval to encorafenib in combination with cetuximab and fluorouracil-based chemotherapy for patients with BRAFV600E-mutant metastatic colorectal cancer, based on results from the Phase III BREAKWATER trial in previously untreated patients.
In this study, the triplet combination demonstrated significant improvements in clinical outcomes, including a 47% reduction in the risk of disease progression or death (HR 0.53) and a 51% reduction in the risk of death (HR 0.49), with median progression-free survival of 12.8 versus 7.1 months and median overall survival of 30.3 versus 15.1 months compared with standard chemotherapy.
Patients Ineligible for Combination Chemotherapy
For patients not suitable for intensive regimens, fluoropyrimidine plus bevacizumab is recommended. In selected patients with RAS-wt, BRAF-wt, left-sided tumors, 5-FU–LV plus an anti-EGFR agent can also be recommended, while anti-EGFR monotherapy may be considered.
Maintenance and Treatment Sequencing
As treatment continues, the focus shifts toward maintaining disease control while minimizing toxicity. Maintenance strategies are recommended after selected induction regimens, particularly fluoropyrimidine–bevacizumab after oxaliplatin-based therapy and fluoropyrimidine–anti-EGFR after FOLFOX–anti-EGFR. These approaches are used to reduce treatment burden while maintaining disease control.
Second-line Treatment Strategy
Second-line treatment in metastatic colorectal cancer is guided by prior therapy and molecular profile, with MMR/MSI status remaining the initial decision point.
For patients with dMMR or MSI-H tumors not previously treated with immune checkpoint inhibitors, immunotherapy is recommended, including nivolumab plus ipilimumab or pembrolizumab.
For patients with pMMR or MSS disease, as well as those with dMMR or MSI-H tumors previously treated with ICIs, treatment is guided by molecular alterations and prior systemic therapy.
In BRAFV600E-mutated tumors, encorafenib plus cetuximab is recommended if not previously used.
For BRAF-wild-type disease, treatment depends on the prior chemotherapy backbone. After oxaliplatin-based therapy, irinotecan-based regimens combined with antiangiogenic agents, including FOLFIRI plus bevacizumab, aflibercept, or ramucirumab, are recommended. After irinotecan-based therapy, oxaliplatin-based doublets plus bevacizumab are recommended.
In patients previously treated with FOLFOXIRI–bevacizumab, second-line options include FOLFIRI–bevacizumab or an oxaliplatin-based doublet plus bevacizumab, while reintroduction of FOLFOXIRI–bevacizumab may be considered in selected patients.
In selected patients with left-sided, RAS-wt, BRAF-wt tumors who have not previously received anti-EGFR therapy, FOLFIRI–cetuximab, FOLFIRI–panitumumab, or irinotecan–cetuximab may also be considered.
Later Lines: The Expansion of Precision Oncology
Treatment beyond the second line in metastatic colorectal cancer is increasingly driven by molecular profiling, alongside prior therapy and patient fitness.
For patients with dMMR or MSI-H tumors who have not previously received immunotherapy, checkpoint inhibitors remain a key option. In contrast, most patients require treatment selection based on molecular alterations or standard later-line therapies.
In molecularly unselected patients, trifluridine–tipiracil (FTD–TPI), with or without bevacizumab, represents a standard approach. In particular, the combination with bevacizumab has demonstrated improved outcomes compared with FTD–TPI alone. After progression, oral multikinase inhibitors such as regorafenib or fruquintinib are recommended options.
For patients with actionable alterations, targeted therapies are preferred when an appropriate agent is available. This includes anti-EGFR–based rechallenge strategies in selected RAS wild-type patients guided by ctDNA, as well as treatments targeting HER2 amplification, KRASG12C mutations, or rare fusions such as NTRK and RET. For POLE- or POLD1-mutated mCRC, nivolumab can also be considered in later lines.
Overall, treatment sequencing in later lines requires an individualized approach, balancing molecular characteristics, prior response, and patient condition, with best supportive care remaining an essential component of management.
This evolving landscape underscores the importance of comprehensive molecular testing both at diagnosis and throughout the disease course.
Follow-Up and Long-Term Care
Follow-up strategies are tailored to treatment intent and disease status. During active therapy, imaging and tumor marker assessments are recommended every 8 to 12 weeks. For patients treated with curative intent, more intensive surveillance is advised, particularly in the first two years.
Beyond disease monitoring, the guideline underscores the importance of supportive care, nutritional management, and long-term survivorship planning as integral components of patient care.
Takeaway
The 2026 ESMO Clinical Practice Guideline highlights the increasing role of precision oncology in metastatic colorectal cancer. Treatment decisions are increasingly shaped by molecular biology, multidisciplinary expertise, and refined therapeutic sequencing. As new biomarkers and targeted therapies continue to emerge, the management of mCRC is becoming increasingly individualized.
The full guideline update is available in ESMO Annals of Oncology.