What are the most recent updates in colorectal cancer treatment, including surgery, adjuvant and neoadjuvant therapy, and systemic options for metastatic disease?

Most Recent Updates to Colorectal Cancer Treatment

The most significant recent advances in colorectal cancer treatment include total neoadjuvant therapy for rectal cancer, neoadjuvant immunotherapy for dMMR/MSI-H tumors, encorafenib plus cetuximab for BRAF-mutated disease, and shortened adjuvant chemotherapy duration (3 months) for selected stage III patients. 1, 2

Neoadjuvant and Total Neoadjuvant Therapy

Rectal Cancer

• Total neoadjuvant therapy (TNT) has emerged as the new standard approach for locally advanced rectal cancer, delivering all systemic therapy before surgery rather than splitting it between pre- and post-operative periods 2
• TNT offers superior local response rates and reduces systemic relapse risk compared to traditional short-course radiotherapy or long-course chemoradiotherapy alone 3, 2
• "Watch-and-wait" non-operative management is now a recommended option for rectal cancer patients achieving complete clinical response after neoadjuvant therapy, though functional outcomes require careful monitoring 3, 2
• Short-course radiation therapy techniques have been expanded with updated recommendations for patient selection 2

Colon Cancer

• Neoadjuvant chemotherapy is emerging for locally advanced colon cancer with proficient mismatch repair, though patient selection remains challenging 4, 3
• For high-risk stage II and stage III colon cancer, neoadjuvant approaches are being actively investigated in trials like FOxTROT, showing potential for better downstaging and improved chemotherapy completion rates 1, 4

Immunotherapy Advances

First-Line Treatment for dMMR/MSI-H Disease

• Pembrolizumab is now the recommended first-line treatment for metastatic CRC with microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR) tumors, replacing chemotherapy as the initial approach 1
• This represents a paradigm shift, as these patients (approximately 15% of metastatic CRC) can achieve long-term disease stabilization with immunotherapy alone 1, 5

Neoadjuvant Immunotherapy

• Neoadjuvant immunotherapy for dMMR/MSI-H colon and rectal cancers is transforming the treatment paradigm, with exceptional pathologic complete response rates and durable responses 4, 3
• This approach is particularly promising for potentially avoiding or deferring surgery in select patients 4

Limitations in MSS/pMMR Disease

• The vast majority of CRC cases (microsatellite stable/proficient mismatch repair) remain resistant to immunotherapy 5
• Research is ongoing to manipulate the tumor microenvironment and tumor stroma to sensitize MSS tumors to immunotherapy 5

Targeted Therapy Updates

BRAF V600E-Mutated Disease

• Encorafenib plus cetuximab is now the recommended treatment for previously treated BRAF V600E-mutant metastatic CRC that has progressed after at least one prior line of therapy 1
• This combination represents a major advance from the BEACON CRC trial, providing strong evidence for MAPK pathway blockade in this poor-prognosis population (approximately 10% of metastatic CRC) 1
• First-line treatment for BRAF-mutated disease remains chemotherapy with bevacizumab, or FOLFOXIRI plus bevacizumab in patients with good performance status 1

RAS Wild-Type Disease and Tumor Sidedness

• For left-sided, treatment-naive RAS wild-type metastatic CRC, chemotherapy plus anti-EGFR therapy (cetuximab or panitumumab) is recommended 1
• For right-sided RAS wild-type disease, chemotherapy plus anti-VEGF therapy (bevacizumab) is preferred over anti-EGFR therapy 1
• Testing for KRAS, NRAS (exons 2,3, and 4), and BRAF mutations is mandatory at metastatic diagnosis, with a recommended turnaround of 10 days 1

Adjuvant Chemotherapy Duration

Shortened Treatment Duration

• For high-risk stage II and low-risk stage III colon cancer, 3 months of adjuvant chemotherapy (particularly with CAPOX) may be considered instead of the traditional 6 months, based on the IDEA study 6, 7, 8
• This represents a significant depotentiation strategy that reduces toxicity while maintaining efficacy 8
• For standard stage III colon cancer, 6 months of FOLFOX or CAPOX remains the standard duration 6, 7

Standard Regimens

• FOLFOX (5-FU/leucovorin plus oxaliplatin) remains the standard adjuvant regimen for stage III colon cancer 6, 7, 9
• CAPOX (capecitabine plus oxaliplatin) is an acceptable alternative with similar efficacy and safety 7

Systemic Therapy for Metastatic Disease

First-Line Options

• For patients appropriate for intensive therapy, doublet chemotherapy (FOLFOX or FOLFIRI) plus bevacizumab is standard, while FOLFOXIRI plus bevacizumab is preferred for fit patients with high tumor burden 1
• Bevacizumab is the preferred anti-angiogenic agent based on toxicity profile and cost 1

Later-Line Options

• Regorafenib or trifluridine-tipiracil are recommended treatment options for patients who have progressed through all available standard regimens 1
• There is no rationale for using panitumumab after cetuximab failure, or vice versa 1

Oligometastatic Disease Management

Liver Metastases

• Perioperative chemotherapy or surgery alone should be offered to patients with potentially curative resection of liver metastases 1
• Stereotactic body radiation therapy (SBRT) may be recommended following systemic therapy for patients with liver oligometastases who are not surgical candidates 1
• Selective internal radiation therapy (SIRT) is not routinely recommended for unilobar or bilobar liver metastases 1

Peritoneal Metastases

• Cytoreductive surgery plus systemic chemotherapy may be recommended for selected patients with colorectal peritoneal metastases 1
• The addition of hyperthermic intraperitoneal chemotherapy (HIPEC) is not recommended, as it does not improve outcomes 1

Critical Molecular Testing Requirements

• All metastatic CRC patients require testing for MMR/MSI status, RAS mutations (KRAS/NRAS exons 2,3,4), and BRAF V600E mutation at diagnosis 1
• MMR/MSI status is particularly critical for stage II patients, as dMMR patients have better prognosis and may not benefit from 5-FU/leucovorin therapy 6, 7
• Primary tumor sidedness (right versus left) should be documented, as it influences treatment selection for RAS wild-type disease 1

Common Pitfalls to Avoid

• Do not use anti-EGFR therapy in RAS-mutated patients, as these mutations are negative predictive factors for response 1
• Do not delay molecular testing—results should be available within 10 days to guide first-line therapy decisions 1
• Do not continue anti-EGFR therapy beyond first progression in right-sided tumors, as efficacy is limited 1
• Do not overlook dMMR/MSI-H testing in all metastatic patients, as these patients should receive pembrolizumab first-line rather than chemotherapy 1
• Do not use bolus 5-FU/leucovorin regimens when infusional regimens are available, as bolus administration carries higher toxicity and mortality risk 6