Extramural extension as indicator for postoperative adjuvant chemotherapy in Stage IIA (pT3N0) colon cancer

The usefulness of adjuvant chemotherapy (CMT) in patients with Stage IIA colon cancer remains unclear. The present study aimed to investigate extramural extension as an indicator for adjuvant CMT. Data were reviewed from 202 consecutive patients with Stage IIA colon cancer that underwent curative surgery between 1995 and 2007. The distance of the extramural extension (DEE) was measured histologically. The optimal prognostic cut-off point of the DEE for oncologic outcomes was statistically determined. The eligible surviving patients had been followed for a median period of 75 months (range: 2-210 months). Patients were subdivided into two groups according to the optimal cut-off point; DEE ≤5 mm (pT3a) and DEE >5 mm (pT3b). The pT3b was the most powerful independent risk factor for postoperative recurrence (P = 0.0324, HR: 3.04, 95% CI: 1.098-8.408), and was significantly correlated with distant metastasis (P = 0.0161 HR: 5.19, 95% CI: 1.765-15.239). The recurrence-free and cancer-specific 5-year survival rates in patients with pT3b were significantly lower than in patients with pT3a (81.5% vs. 95.4%, P = 0.0003 and 85.9% vs. 97.4%, P = 0.0007, respectively). pT3b could be an important risk factor for distant metastasis in Stage IIA colon cancer. Postoperative adjuvant CMT may be indicated for patients with pT3b.