The New England Journal of Medicine June 03, 2004

Oxaliplatin, fluorouracil, and leucovorin as adjuvant treatment for colon cancer

Thierry André, Corrado Boni, Lamia Mounedji-Boudiaf, et al.

Bottom Line

The addition of oxaliplatin to fluorouracil and leucovorin (the FOLFOX4 regimen) significantly improves disease-free survival in patients with resected stage II or III colon cancer.

Key Findings

1. At a median follow-up of 37.9 months, the 3-year disease-free survival rate was significantly higher in the FOLFOX4 group compared to the fluorouracil and leucovorin (FL) group (78.2% vs. 72.9%; P=0.002).

2. Patients receiving FOLFOX4 experienced a 23% reduction in the risk of recurrence compared to those receiving FL alone (Hazard Ratio 0.77; P=0.002).

3. Cancer-related events occurred in 21.1% (237 of 1,123) of patients in the FOLFOX4 group versus 26.1% (293 of 1,123) in the FL group.

4. Grade 3 sensory neuropathy was observed in 12.4% of patients receiving oxaliplatin during treatment, but this decreased significantly to 1.1% at one year of follow-up.

5. The incidence of febrile neutropenia in the FOLFOX4 group was low (1.8%), and the death rate during treatment was identical in both study arms (0.5%, or 6 patients in each group).

Study Design

Design

RCT

Open-Label

Sample

2,246

Patients

Duration

37.9 mo

Median

Setting

Multicenter, International

Population Patients aged 18-75 years who had undergone complete curative resection of histologically proven stage II or stage III colon cancer.

Intervention Fluorouracil and leucovorin combined with oxaliplatin (FOLFOX4 regimen) administered every 2 weeks for 12 cycles (6 months).

Comparator Fluorouracil and leucovorin (FL / LV5FU2 regimen) administered alone every 2 weeks for 12 cycles (6 months).

Outcome Disease-free survival (DFS)

Study Limitations

• The trial utilized an open-label design, which could introduce bias in the reporting of subjective toxicities such as peripheral sensory neuropathy.

• The initial 2004 report primarily established a disease-free survival (DFS) benefit; overall survival (OS) data were immature at the time of publication and required subsequent long-term follow-up reports.

• While the benefit of oxaliplatin was clear for stage III disease, the absolute benefit for stage II patients was small, leading to ongoing debate regarding the routine use of oxaliplatin in average-risk stage II colon cancer.

• The study did not originally stratify patients by mismatch repair (MMR) status or microsatellite instability (MSI), which are now recognized as critical biomarkers for determining the benefit of adjuvant chemotherapy in stage II disease.

• While grade 3 neuropathy largely resolved, mild-to-moderate persistent neuropathy remains a chronic issue for a subset of patients that was not fully captured by the primary endpoint.

Clinical Significance

The MOSAIC trial was a paradigm-shifting study that established the FOLFOX regimen as the new global standard of care for the adjuvant treatment of resected stage III colon cancer. By demonstrating a clear and significant absolute improvement of 5.3% in 3-year disease-free survival over the previous standard of 5-FU/LV alone, the trial proved that intensifying therapy with oxaliplatin could cure more patients with early-stage disease. It also properly characterized the reversible nature of oxaliplatin-induced neurotoxicity, giving clinicians the confidence to administer the regimen broadly.

Historical Context

Prior to the MOSAIC trial, 6 months of fluorouracil and leucovorin (5-FU/LV) had been established as the standard adjuvant therapy for colon cancer following pooled analyses in the 1990s. However, recurrence rates remained frustratingly high, particularly for node-positive (stage III) disease. Oxaliplatin, a third-generation platinum derivative, had recently shown strong efficacy in metastatic colorectal cancer. Published in 2004, the MOSAIC trial successfully translated this benefit into the early-stage, curative-intent setting. This landmark publication redefined gastrointestinal oncology pathways and paved the way for modern risk-stratified treatment approaches in colorectal cancer.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

What is the primary mechanism of action of oxaliplatin compared to 5-fluorouracil, and what is the classic dose-limiting toxicity of oxaliplatin that patients must be counseled on before starting the FOLFOX regimen?

Key Response

Oxaliplatin is a platinum-based alkylating-like agent that forms DNA cross-links, preventing replication and transcription, whereas 5-fluorouracil is an antimetabolite that inhibits thymidylate synthase. The classic dose-limiting toxicity of oxaliplatin is a cumulative, dose-dependent peripheral sensory neuropathy that is often uniquely triggered or exacerbated by cold exposure. Understanding this is essential for board exams and basic clinical reasoning.

Resident

The MOSAIC trial established FOLFOX as a standard of care for adjuvant therapy, but the benefit in Stage II disease is much less clear than in Stage III. How do you clinically risk-stratify patients with Stage II colon cancer to decide whether to offer adjuvant FOLFOX?

Key Response

While FOLFOX clearly benefits Stage III (node-positive) patients, the absolute benefit in Stage II is small. Residents must identify high-risk features of Stage II colon cancer to justify chemotherapy, which include T4 tumor status, inadequate lymph node sampling (less than 12 nodes examined), bowel perforation or obstruction at presentation, poorly differentiated histology, perineural or lymphovascular invasion, and importantly, microsatellite stable (MSS) disease, as MSI-high patients generally do not benefit from adjuvant 5-FU.

Fellow

While the initial MOSAIC trial demonstrated a significant improvement in 3-year disease-free survival (DFS), how did the long-term overall survival (OS) data differ between Stage II and Stage III cohorts, and how did oxaliplatin-induced toxicity eventually lead to modern de-escalation trials like the IDEA collaboration?

Key Response

Long-term follow-up of MOSAIC proved an OS benefit for Stage III patients but failed to show a statistically significant OS benefit for the overall Stage II population. Because oxaliplatin causes long-lasting, sometimes irreversible peripheral neuropathy, the oncology community launched the IDEA collaboration to determine if 3 months of adjuvant therapy is non-inferior to the 6 months used in MOSAIC, attempting to mitigate neurotoxicity without compromising survival.

Attending

When counseling an elderly patient with low-risk Stage III colon cancer, how do you weigh the absolute disease-free survival benefit of adding oxaliplatin against the risk of permanent neuropathy, and what is your threshold for de-escalating therapy in practice?

Key Response

Attendings must navigate the 'art of oncology' through shared decision-making. The absolute DFS benefit of adding oxaliplatin is around 7-8%, but severe permanent neuropathy can drastically impair quality of life in older adults. Teaching points for trainees include assessing biological age, utilizing the 3-month IDEA data for lower-risk disease, and proactively dropping oxaliplatin early if grade 2 neurotoxicity develops, completing the remainder of the 6-month course with fluoropyrimidine alone.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The MOSAIC trial utilized 3-year disease-free survival (DFS) as its primary endpoint, which later became widely accepted as a valid surrogate for 5-year overall survival (OS) in colon cancer. Statistically, what criteria must be met to validate a surrogate endpoint in oncology, and what are the limitations of relying on DFS in the modern era of highly effective salvage therapies?

Key Response

Validating a surrogate requires demonstrating both patient-level correlation and trial-level correlation (e.g., using Prentice criteria or meta-analytic approaches). A major limitation in modern trial design is that highly effective post-recurrence salvage therapies (targeted therapies, immunotherapy, metastasectomy) can dilute the OS signal. Thus, an intervention might improve DFS but show no OS benefit if the salvage treatments are highly effective or if the adjuvant therapy alters the biology of the recurrence, making it more resistant.

Journal Editor

As a peer reviewer for the original MOSAIC manuscript, how would you critique the open-label design of the trial, particularly regarding the ascertainment of subjective secondary endpoints like oxaliplatin-induced peripheral neuropathy?

Key Response

Because the trial was open-label, the reporting of subjective adverse events like neuropathy is highly susceptible to ascertainment and reporting biases. An editor would flag the need for standardized, objective neurotoxicity grading scales and patient-reported outcomes (PROs). Furthermore, lack of blinding could influence investigator behavior regarding dose modifications and early trial discontinuation, potentially skewing the safety and tolerability profile.

Guideline Committee

How has the foundational evidence from the MOSAIC trial been synthesized with recent data in current NCCN and ASCO guidelines regarding the duration of adjuvant FOLFOX therapy for Stage III colon cancer, specifically differentiating between low-risk (T1-3, N1) and high-risk (T4 or N2) categories?

Key Response

MOSAIC established 6 months of FOLFOX as the Category 1 recommendation for Stage III colon cancer. However, current NCCN and ASCO guidelines have updated this based on the IDEA collaboration. For low-risk Stage III (T1-3, N1), guidelines now support a shorter 3-month duration of CAPOX (or 3-6 months of FOLFOX) to reduce neuropathy, while 6 months of FOLFOX or CAPOX remains strongly recommended for high-risk Stage III (T4 or N2) disease where the recurrence risk outweighs the cumulative toxicity.

Clinical Landscape

Noteworthy Related Trials

2007

NSABP C-07 Trial

n = 2,407 · J Clin Oncol

Tested

Fluorouracil, leucovorin, and oxaliplatin (FLOX)

Population

Patients with stage II or III colon cancer

Comparator

Fluorouracil and leucovorin (FULV)

Endpoint

Disease-free survival (DFS)

Key result: The addition of oxaliplatin to bolus fluorouracil and leucovorin significantly improved disease-free survival.

2011

NO16968 (XELOXA) Trial

n = 1,886 · J Clin Oncol

Tested

Capecitabine plus oxaliplatin (XELOX)

Population

Patients with resected stage III colon cancer

Comparator

Bolus fluorouracil and leucovorin

Endpoint

Disease-free survival (DFS)

Key result: XELOX significantly improved disease-free survival compared to standard 5-FU/LV, showing an orally administered fluoropyrimidine is an effective substitute.

2018

IDEA Collaboration

n = 12,834 · NEJM

Tested

3 months of oxaliplatin-based chemotherapy (FOLFOX or CAPOX)

Population

Patients with stage III colon cancer

Comparator

6 months of oxaliplatin-based chemotherapy

Endpoint

Disease-free survival (DFS)

Key result: Non-inferiority of 3 months of therapy was not confirmed overall, but 3 months of CAPOX was sufficient for low-risk stage III disease with markedly less neurotoxicity.

Tailored to your role

Want this tailored to you?

Add your specialty or training stage to get role-specific takeaways and more questions.

Personalize this analysis