In stage 2 colon cancer, and especially in stage 2a colon cancer, there are several high risk features that—if present—would support the case for giving adjuvant chemotherapy (e.g. FOLFOX). These include:

Clinical high risk features

  • Patient presents with bowel obstruction or perforation
  • High pre-operative CEA (over 5 ng/ml)

Pathological high risk features

  • Close, indeterminate, or positive operative margins
  • Less than 13 lymph nodes found in specimen
  • T4 primary

Histological high risk features

  • Lymphovascular invasion
  • Perineural invasion
  • Poorly differentiated tumor
  • Signet ring or mucinous tumor

The presence of one, two, or more of the above features portends poorer prognosis. For instance, patients with stage 2a colon cancer but with 2 or more of the above features can have worse prognosis than patients with stage 3a or 3b colon cancer, especially if they do not receive adjuvant chemotherapy.

References

Christine M. Ribic et al. Tumor Microsatellite-Instability Status as a Predictor of Benefit from Fluorouracil-Based Adjuvant Chemotherapy for Colon Cancer. NEJM 349(3):247-257 (2003). PMID 12867608

S. Popat et al. Systematic Review of Microsatellite Instability and Colorectal Cancer Prognosis. JCO 23(3):609-618 (2005). PMID 15659508