A 65-year-old woman with resected stage II colorectal cancer (T3N0M0) is being counseled about adjuvant therapy. She has no contraindications to chemotherapy. Which is the preferred adjuvant regimen?

Question

Accepted Answer

C. FOLFOX (5-FU + Leucovorin + Oxaliplatin). ## Adjuvant Chemotherapy for Stage II Colorectal Cancer

**Key Point:** FOLFOX is the preferred adjuvant regimen for stage II colorectal cancer with high-risk features (T3N0 or T4 tumors, poor differentiation, lymphovascular invasion, or microsatellite stability).

### Stage II Risk Stratification

**High-Risk Stage II** (like this patient's T3N0):
- Tumor depth ≥T3
- Poor histologic differentiation
- Lymphovascular or perineural invasion
- Inadequate lymph node sampling (<12 nodes)
- Microsatellite stable (MSS) or proficient mismatch repair (pMMR)

**Benefit of FOLFOX in High-Risk Stage II:**
- Reduces recurrence risk by ~20%
- Improves disease-free survival (DFS) by 3–5 years
- Absolute benefit: ~3–5% at 5 years
- Supported by ASCO, ESMO, and NCCN guidelines

### Adjuvant Regimen Comparison

| Regimen | Indication | DFS Benefit | Toxicity |
|---------|-----------|-------------|----------|
| **5-FU monotherapy** | Obsolete; rarely used | Minimal | Low |
| **5-FU/LV** | Stage III; low-risk stage II | Modest | Low |
| **FOLFOX** | High-risk stage II; all stage III | Superior | Moderate (neuropathy, myelosuppression) |
| **Bevacizumab + chemo** | Not standard adjuvant; mainly metastatic disease | Not established | Higher |

**High-Yield:** Stage II T3N0 is considered "high-risk" and warrants FOLFOX, not just 5-FU/LV. The oxaliplatin component is critical for improved outcomes.

**Mnemonic: FOLFOX for HIGH-RISK Stage II** — **F**luorouracil, **O**xaliplatin, **L**eucovorin for tumors with **H**igh-risk features (T3/T4, poor grade, LVI).

**Clinical Pearl:** Stage II low-risk (T1–T2, good differentiation, no LVI, adequate nodal sampling) may be observed without adjuvant therapy; high-risk stage II requires FOLFOX.

[cite:ASCO Colorectal Cancer Adjuvant Therapy Guidelines; NCCN Colorectal Cancer v3.2023]

Answer

A. 5-Fluorouracil + Leucovorin (5-FU/LV)

Answer

B. Bevacizumab + 5-FU/LV

Answer

D. 5-Fluorouracil monotherapy

A 65-year-old woman with resected stage II colorectal cancer (T3N0M0) is being counseled about adjuvant therapy. She has no contraindications to chemotherapy. Which is the preferred adjuvant regimen?

Explanation

Adjuvant Chemotherapy for Stage II Colorectal Cancer

Stage II Risk Stratification

Adjuvant Regimen Comparison

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Regimen	Indication	DFS Benefit	Toxicity
5-FU monotherapy	Obsolete; rarely used	Minimal	Low
5-FU/LV	Stage III; low-risk stage II	Modest	Low
FOLFOX	High-risk stage II; all stage III	Superior	Moderate (neuropathy, myelosuppression)
Bevacizumab + chemo	Not standard adjuvant; mainly metastatic disease	Not established	Higher